Full Spectrum Laser 40W 4th Gen - Dead USB

Hi - I have a 4th gen FSL laser. It appears that the mini USB connector is delaminating from the PCB (top board in pic). FSL is checking to see if they have a replacement board, but they've already mentioned a $750 cost for replacing this thing. Other than the dead board, the laser works well enough especially for its age.

My questions:

1) The board has a DB9 connector pinout exposed - does anyone know if I could use a USB --> Serial and connect to the DB9 pinouts to avoid the USB situation?

2) Any recommendations on an alternative controller board to drive the laser instead? For giggles I picked up a cheap GRBL board on amazon that seems capable of running the stepper motors, but I'm not clear how (or if) I can use it to turn on the laser. Does anyone have a pinout explanation for the laser driver and what pins I need to talk via to drive the laser?

3) If I can't figure out how to talk GRBL or eqiv to the laser controller, I was considering using the spindle on/off relay on the GRBL board and wire the relay around the physical "laser test" switch. I mostly cut w/ the laser instead of engrave - so I could use the power adjust pot on the machine to set laser power and the laser test button as on/off (except using the relay). Any reason this wouldn't/shouldn't work?

Thanks!

That board is special for FSL and will be the only one to run their software. A good electronics guy could solder a new connector on it, (much cheaper than $750). The DB9 is usually used for serial connection what does your owners manual say?

Sorry your in trouble with that crap company there rip off artist