Greetings, Car cut out while driving, Stability control failure popped up

Hello everyone, I am looking for some advice, I apologise in advance for the long post and also that I am new to cars and the terminology so will probably get a few things wrong.

I recently got my first saab about 2 months ago (9-3 2.0t sport wagon 2010) all the service history looked good, drove great and had done a few cross country trips alongside work commutes with no complaints.
Got a remap done and it drove even better, then out of the blue after I dropped my gf off it went completely dead on me, with traction control failure and stability control failure flashing up on the display.
Managed to push it home but insurance won't cover a breakdown call out as they don't cover home breakdowns (fuming)

So, what I have done so far is, try disconnect battery for 15 mins to reset the errors, check the connectors to the ecu, looked at the fuse box and tried a paper clip bridging between certain connectors ( think this threw up steering lock failure instead of the other failures) I then tried disconnecting the abs part in the engine bay and bridging with 2 paperclips on the last four ports, when trying to start it said 'Checking- Checks all ok' or something to that effect but no signs of the engine starting.

Side note I wanted to removed the tray that the battery sits in and saw the four torx bolts were fully stuck, tried using my impact driver on it but ended up breaking the magnetic bit holder (was an old one)
So additional question, if I wanted to remove that to get access to look at wiring, would it be a case of drilling the bolts out entirely?
I can take some pictures tomorrow to clarify what I'm banging on about.
But any help would be massively appreciated.

Sorry to hear this. Pictures would make the situation more clear. I wonder if the remap was part of the problem.