Powers up plugged in, but not on battery (but runs on battery after power-up)

[mraikes]

I have a customer's HP/Compaq CQ62 laptop (approx 2-3 years old) that came in for a hard drive replacement - done & fine.

In a "by the way" remark, customer mentions the laptop won't power up unless it's plugged in. If on battery only, the power switch does nothing. If plugged in, the power switch works as usual. And after it starts up, the laptop can be disconnected from mains power and runs great on battery for at least a couple hours.

The customer doesn't want to spend much money on the problem - he's already learned to live with it. So I can't spend a lot of time on it, but if anyone has encountered this before and has suggestions - I'm wide open.

Troubleshooting? None really other than confirming the problem.

Theory #1: Battery is failing to put out enough juice to boot, but trickles out enough to keep it running. Challenge: I can't think of a way to test this without a new battery.

Theory #2: Capacitor problem rather than the battery. If lucky, I'd see obvious blown/bulging capacitors on the MB. Challenge: No budget for a teardown, plus I've not actually seen this as a symptom of bad laptop capacitors.

Theory #3: Bad switch. But I really can't think of any switch failure that would differentiate between battery and mains power.

Am I missing some other likely culprit?

[DCGPX]

Does this model have a separate power board? Might be worth checking and try replacing that if it does.

Just doing some work on my server otherwise I'd check the manual as they're on it!

Edit : Yes it does have a separate Power board, might be worth checking that as a cheap option

[Rob_NNCC]

I came across a Compaq laptop that had exactly this problem. The battery had been removed then dropped. If the battery was inserted back into the laptop and pushed on in a certain way, it would make the correct contact and the laptop would boot up.

Here are a few other things this laptop did. If it was plugged in, the charge light would not come on unless the battery was pressed in this particular way. Windows would not recognize the battery unless pressed in the particular way...

[mraikes]

Good suggestions and nice low budget possibilities to investigate.

Thanks!