Can't Upload Marlin to Ultimachine Board RAMBo v1.4

I bought this board/endstop kit https://ultimachine.com/products/rambo-1-4?_pos=1&_sid=14d6aa83e&_ss=r due to it not being available in the shop at the time of order.

Trying to flash this Marlin version https://github.com/tormodhau/Marlin-MPCNC/tree/MPCNC_Rambo_T8_16T_LCD with a bare board connected via USB and keep getting the below error:

Sketch uses 107760 bytes (42%) of program storage space. Maximum is 253952 bytes.
Global variables use 4518 bytes (55%) of dynamic memory, leaving 3674 bytes for local variables. Maximum is 8192 bytes.
An error occurred while uploading the sketch
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer

My build has 20t pulleys at the moment so I changed the line for steps to 80 80 400 80 but other than that I made no changes to the code.

I assumed USB only would be adequate to power the board for upload but if that’s not the case please advise.

Just in case anyone has the same problem… You can’t upload it without an independent 12v power source connected. Once powered the upload went through fine.

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Nope. The 12V is isolated from the USB on these boards, so the micro isn’t powered from the USB.

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