I have no idea why this may be but the below may be of some help
Bought HP G62 second hand with a defective battery so fitted one from previous HP laptop
Discovered the flickering only happened when plugged into mains so unplugged from mains and flickering disappeared - tested repeatedly and definitely the case
But battery charge when disconnected seems to drop rapidly so plugged back in ad no flickering as yet
My suspicion is that a fully charged battery whilst still connected is causing issue - so power management circuitry would appear to be at fault - is battery trying to overcharge?
I've a certain amount of diagnostic experience around suitably 'obscure' issues - I'm convinced the reason why my sound has gone in my 21 year old XJ6 is that Jaguar in their wisdom decided to mute sound unless the audio system detected aerial was extended!