Probably a common Monster issue but...

Hi All

My 2003 Monster 620ie has an intermittent electrical issue that I’ve read quite a lot about online, but no successful fixes. Hoping someone understands the problem:

Once every while, without any obvious pattern, the electrical system goes completely dead when attempting to switch on. Like there’s no battery connected - not even yellow immobiliser light flashes. No dash lights or dial spins when I insert the key. Another day, it will be fine.

Stuff I’ve tried:
- new battery
- replaced rec/reg with new MOSFET unit
- fiddled with and checked every visible connection I can see

No luck. I know the battery and new reg work because they fired up the first time then I switched off and the system went completely dead again.

Welcome q y advice and experience of this.


Cheers