No recovery window

Offhand, I'd guess the drive has failed. If you have an external drive with macOS installed, then try booting from it. If your model can do Network Recovery, then try:

Internet/Network Recovery on Erased Disk

     If possible back up your files before proceeding.

1. Restart the computer. Immediately after the chime hold down the (Command-Option-Shift-R) keys until a globe appears.
2. The Utility Menu will appear in from 5-20 minutes. Be patient.
3. Select Disk Utility and click on the Continue button.
4. When Disk Utility loads select the target drive (will be the out-dented entry) from the side list.
5. Click on the Erase tab in Disk Utility's main window. A panel will drop down.
6. Set the partition scheme to GUID.
7. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
8. Click on the Apply button, then click on the Done button when it activates.
9. Quit Disk Utility and return to the Utility Menu.
10. Select Install OS X and click on the Continue button.

If the battery screw heads are above the battery surface, you could try using a pair of pliers or miniature vise grips to loosen the screws. Just be careful not to have them make contact with the Logic Board.

My guess is your GPU has finally decided to die. This model is known for their GPU issues.

Another user on these forums has posted detailed instructions on how to disable the discrete GPU and use the Intel GPU instead which may allow you to bypass the issue. IIRC one of his instructions involved using Linux to reconfigure the GPU settings if the system was not bootable and the user had no bootable external USB or Firewire drive.

If Kappy is correct and the drive is failing, you can check the health of the hard drive by creating a bootable Knoppix Linux USB drive using Etcher. (I did not consider it since your Internet Recovery attempt was also unsuccessful). Option Boot the Knoppix USB drive and select the orange icon labeled "EFI". Once at the Knoppix desktop, click on the "Start" menu in the lower left of the Taskbar and navigate to "System Tools --> GSmartControl". Double-click your drive in GSmartControl to see its health. Feel free to post a screenshot or picture of all the attributes listed on the "Attributes" tab. Also check to see if any errors are listed on the "Error Log" tab.

Note: Knoppix may not boot on this model laptop if the GPU has issues. If Knoppix manages to boot to the command line instead of the desktop, then you can type the following command to view the SMART Attributes.

sudo  smartctl  -A  /dev/sda  |  less

Use the up & down arrows to scroll through the report so you take pictures of the attributes. Press "q" to quit. To shutdown the system you can type the following command or just press & hold the power button.

sudo  shutdown  -h  now