somebody else tried to start my MR2-W3-2000. They used a wrong battery, with the PLUS and MIN turned over

[mabu66]

Last week somebody else tried to start my MR2-W3-2000.
They used a wrong battery, with the PLUS and MIN turned over, I have the right battery here at home.

What's not working at all:
radio, flashing lights (warning lights burn!), dashboard lights, rear lights, power steering, "warning sound beeps" OBD2 and maybe more.

No broken fuses,  or is the ECU broken, and if so, how do I check (measure?)
Or has everything another cause?

Auto just start normal !!