My Bosch AL2450 DV was dead. R3 was burnt so replaced 180K resistor.
Now powers on and shows 41V output between + & - contacts.
Also, between the + and NTC contact 36V, between the - and NTC contact 5V.

Green light ON indicating ready to charge - then plug in either battery and the Green light goes OFF and the Red light goes ON and stays on for both batteries.

What should I check next ? The N-Channel MOSFET or something else ?
Thanks for your help - trying to fix this for my neighbour.

David, January 2023

"Burning" a 180k resistor would need an inordinately high voltage. I suspect a number of things:
A "burnt" resistor, unless it is in a mains voltage circuit, will be significantly less than 180k
Whatever caused the resistor to burn is still faulty and may well have taken more components down.
Randomly replacing components is a sure fire way of burning through money to no effect.
You need a circuit diagram, either a published one or one you've prepared for yourself. Then you need to understand it.
Personally I'd trawl eBay for a working charger.

Gghu, January 2023