If the battery was installed backwards, what issues could prevent a 2001 VW Jetta VR6 from starting, after correcting the issue?
It can blow main fuses first, then fry all instrumentation, computers, alternators, basically anything electrical. So use an ohm meter an physically test each main fuse in the main power distribution box first, that means removing each and everyone of them, then test all of the other fuses. Hopefully no damage was done other than main fuses.
I've seen this happen...swap the ECU...if it hasn't completely failed, it's on the way to doing so.
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