MP Maker Select v2 Marlin Installation gone wrong

I finally decided it was time to upgrade the firmware on my maker select to get all the proper safety features enabled. I uploaded a bootloader to the machine (note, I used a raspberry pi for this, not an arduino because it is what I had available). That succeeded. So I connected the printer to my computer, change settings as necessary in marlin, compiled, and uploaded. The printer turns on (no lcd as I burned that out accidentally awhile ago) and I can attempt to connect to USB with octoprint, but octoprint recirved a garbled message back from the printer. If anyone has any advice for how to troubleshoot this that would be much appreciated. I haven't found any information on a printer spitting out malformed messages from USB yet.

I just let you know I am facing this problem too with my printer. Thank you!