You most likely have a brick, as in a corrupted BootROM/SPI flash. Obtain the Apple Technician Information on your 2010 Mac Professional, go to the a part of the Minimal Configuration Testing and test the diagnostic LEDs, round web page 28 to 33 if I bear in mind appropriately.
See what LEDs are lit and what are off, then comply with the diagnostic steps that Apple counsel.
Along with your described signs, my guess is that your EFI DONE diagnostic LED is off and you’ve got a brick.
GPU defects could make a Mac to not boot in a means that’s similar to a brick, test with one other know working GPU earlier than attempting to desolder/reprogram the SPI flash or shopping for substitute backplanes/Mac Professional MATT card.