How to reboot unresponsive 2019 MacBook Pro with no physical buttons?

At the end of the Touch Bar is power/TouchID button.

Press deeply and hold for ten seconds to definitely power OFF.

if the battery got so low that it powered off by itself, there may not be enough power remaining in the system to start up. And paradoxically, not enough to initiate a regular Charge Cycle.

The battery is wired right into the heart of MacBook Pro power, and used to smooth out the DC power. The battery MUST have at least a small charge, or your Mac can not start a processor to do anything, not even start a charge cycle.

General advice is to connect to power adapter and leave it for many hours, such as overnight, in hopes that it can trickle-charge enough to start up and begin a regular charge cycle and build the power level back up more quickly.

for Intel Macs, an SMC reset may help things along.

Reset the SMC of your Mac - Apple Support

RF-tech wrote:

What you mentioned above seems to be what happened. But usually I receive messages that the battery is low before we get too “no battery.”

If the Battery has never been replaced....or the Top Case/Keyboard Assembly which contains the Battery, then you have an original battery from the factory that is at least 5 to 7.5 years old depending on the exact model of this MBPro 2019 model laptop. Most Lithium batteries usually need to be replaced at 3-5 years old although some may last longer depending especially if the user only requires a couple hours or battery runtime.

This means the battery is very likely wearing out or even beginning to fail. Option-click the Battery icon on the menu bar to see if it shows "Service Recommended". You can also try running the Apple Diagnostics to see if any hardware issues are detected. If either "Service Recommended" is shown, or a battery failure is detected by the diagnostics, then combined with your symptoms it is likely the battery needs to be replaced.

Even if macOS & the diagnostics do not show any problems.....the battery could still be wearing out or failing.

I will also investigate the SMC reset.

FYI, I find it useful to Option Boot the laptop by holding the Option key down immediately after hearing the startup chime. While the laptop is at the Apple boot picker menu, perform the SMC Reset. I do this because when you press & hold the three keys......when you finally press the power button the laptop should immediately power off if the SMC Reset was performed successfully. Otherwise it can be hard to tell if it was done correctly.

Also, after performing an SMC Reset of a T2 Mac (generally a 2018-2020 Intel Mac) you should wait about 15 seconds before attempting to power on the laptop again. Sometimes it can be a bit tricky getting the laptop to power on the first time. You can try to wait a bit longer, but if you still have issues, then disconnect the charging cable from the laptop for 15 seconds, then reconnect it. That typically will trigger the laptop to power on assuming the battery has sufficient charge (in your case I would make sure the battery had 80%-100% to be safe).

Do you hear a "ding" sound when connecting the power cable to the laptop? Wait a couple of minutes just in case there is a delay (usually it will ding after about 5-10 seconds). Try each USB-C port, but especially one on the other side. Also, try rotating the USB-C connector of the charging cable 180º upside down just in case the port/cable is half bad. If you don't hear a "ding" sound, then most likely you have a hardware issue of some sort (laptop, power adapter, USB-C charge cable, or an electrical issue with the electrical outlet).

When performing the SMC Reset mentioned by @Grant, make sure to follow the instructions for a T2 laptop as they are different from older Intel models.

Try connecting an external display just in case the built-in Display Assembly is bad. Any video on the external?

You can also try pressing the Caps Lock key to see if its LED lights up when you think the device should be powered on. Give it at least 30 seconds after "power on" to try, but don't wait too long since these Macs can power off very quickly if left at the login screen. If the Caps Lock LED lights up or there is video on the external display, then the system is powering on, which may give us more troubleshooting options.

What is the exact model of this laptop? 13", 15", or 16"? The 16" model certainly has a much higher rate of failure than the others. You can use the Apple check coverage page to confirm the exact model:

View Coverage - AppleCare & Warranty

You can have Apple examine the laptop to confirm a hardware failure. However, I do not recommend repairing any Intel Macs for multiple reasons as the money spent on repairs is much better put towards a new laptop.

The 'gas gauge' is a very coarse measure of battery charge levels, and those levels vary with time and temperature, so the next time you look the reading WILL be different.

System Management [micro-]Controller (SMC) controls fans, power, charging and processor clock speeds in an Intel Mac.

SMC Reset can only help, and can be applied many times without damage or any issues.

RF-tech wrote:

The laptop is definitely old enough for a replacement battery. Let it charge overnight and woke up ok with 100%. The battery % wasn’t solid and shows signs the battery isn’t happy.

I will look into changing that out.

Appreciate all the good troubleshooting help..!

see Vintage and Obsolete:

Vintage—Apple will repair if parts are available; Obsolete—no.

Obtaining service for your Apple product after an expired warranty - Apple Support

Get help with your Mac notebook battery

Learn how to optimize the life of the battery in your Mac notebook, fix battery issues, and get service.

If you see battery 'Service Recommended' on your Mac laptop - Apple Support

RF-tech wrote:

The laptop is definitely old enough for a replacement battery. Let it charge overnight and woke up ok with 100%. The battery % wasn’t solid and shows signs the battery isn’t happy.

I will look into changing that out.

Appreciate all the good troubleshooting help..!

FYI, an official Apple battery repair/replacement will also include a new Top Case/Keyboard Assembly since the battery is glued to it. This is great for the 13" & 15" 2019 models since an official battery repair will give you a fresh keyboard as those models use the dreaded butterfly keyboards which have lots of issues. IIRC, the 16" model actually went back to using the more reliable & traditional scissor mechanisms for the keyboard.

If an official Apple battery replacement is no longer available, then be very careful with any third party batteries since the quality of third party batteries is extremely poor even when purchased from a respected vendor such as OWC or iFixIt. I would not purchase batteries from anywhere else....the quality is that bad (even if someone sells a good battery one time, the next time that same vendor can give you a bad one). Professional installation is highly recommended.

Normally I don't recommend spending any money on repairs for any Intel Mac (especially USB-C models) for multiple reasons. A battery replacement is one of those borderline......it may be worthwhile if the device has no other problems.....maybe.

HWTech wrote:

Normally I don't recommend spending any money on repairs for any Intel Mac (especially USB-C models) for multiple reasons. A battery replacement is one of those borderline......it may be worthwhile if the device has no other problems.....maybe.

One of the problems with spending money on a 2019 Intel Macbook Pro is that they cannot advance past Tahoe. I have one of those (16" model), it is excellent condition and running well, and the battery (always on Apple's battery health management) has been at 85% capacity for about a year now, almost like it has settled or plateaued at that level. It also is on an AppleCare One plan for multiple devices, so I guess a battery replacement would be very low cost (if not fee) for me. I am seriously considering just waiting for the M6 MacBook Pro and replacing it with that ...