Panacutt Azteeg X3 Pro issues (2 replies)

I believe I've invested due diligence into basic troubleshooting. I have another printer up and running, so I'm not completely new to this...

Last week I recieved my X3 Pro, and have had issues, unfortunately documentation and even forum postings regarding this board are lacking.

When attempting to upload marlin firmware (Com5, Arduino Mega 2560 or Mega ADK), I'm receiving the following error:

avrdude: verification error, first mismatch at byte 0x0000
0x0c != 0x14
avrdude: verification error; content mismatch

When attempting to update the bootloader, I recieve the following error:

avrdude: stk500_getsync(): not in sync: resp=0x00

I've attempted a reset, I've attempted both of these operations with none of the stepper drivers on the board, I have the input Sel jumper set to USB.

I've attempted to find documentation for the initial setup of this board in case I missed something unsuccessfully.

LED 3 does blink in 2 sets of 2 blinks once a second, when attempting to upload the firmward, it does indicate data transfer, but errors out as indicated above.

Kinda stuck at this point.

Any ideas?