MegaPi Flashing Help

I'm trying to flash a new version of Marlin to my laserBot with a MegaPi controller board.

My current flash string times out:

/K cd\ & cd bencutlaser & avrdude -p m2560 -c stk500v2 -P COM4 -b 115200 -D -U flash:w:Marlin110RC8.hex:i

I'm not sure what changes I need to make?

Thanks for any help!