Mac Pro 2010 power issue

Hello ssng,

For issues where you cannot power your Mac on like normal, we advise checking the helpful steps in this article which can help with that issue: If your Mac doesn't turn on - Apple Support. Follow this guidance:

1. "Check power connections: Make sure that your power cable is undamaged and plugged securely into your Mac and a working electrical outlet. If your Mac has no built-in display, make sure that your external display is connected to power, connected to your Mac, and turned on.
2.  Press and hold the power button: Press and hold the power button on your Mac for about 10 seconds. (Every Mac has a power button. On laptop computers that have Touch ID, press and hold Touch ID.)
3. Then press and release the power button normally.
4.  Unplug accessories: You could have an issue with one or more accessories or their cables. Unplug all accessories from your Mac, including printers, drives, USB hubs, and mobile devices. Then repeat step 2, above.
5.  If you see something on your screen: If your screen shows a flashing question mark, circle with a line through it, or anything else, your Mac is turned on but isn't starting up: If your Mac turns on but doesn't start up all the way.
6.  If you see nothing on your screen: If your Mac seems to be turned on but the screen remains blank, the issue could be software related:If your Mac starts up to a blank screen.
7.  Reset the SMC (Intel-based Mac only): If you're using an older, Intel-based Mac, resetting the SMC might help: Reset the SMC.
8.  Contact us: If your Mac still doesn't turn on, contact Apple Support."

From what you described, it sounds like Step 4 might come into play: an issue with an accessory. While it is not common for accessories or peripherals to cause issues of this type, it's certainly possible. We would advise contacting the manufacturer to see if there may be a firmware update or something available that might help with this behavior.

Let us know if we can help with anything else at all or if this doesn't settle your issue so we can look into this further with you. Thanks and have a fabulous day!