L502x in constant boot loop

Unplug the system, remove or disconnect the battery and hold the power button for 30 sec.

Remove and reinstall the memory modules.

Power up again -- if you still get the same issue, try one memory module at a time in each socket until you isolate the bad module (which you'll need to replace) or the bad socket (in which case, replace the mainboard).

If that does nothing, replace the main system board.

Thanks ejn63, I'll give that a try. -Nick

Tried removing each memory module and reinstalling into different sockets (all 4 combinations) but the issue still persists. Replacing the main system board: is this straightforward enough? Worth it for a laptop this age? (paid 1000 CAD back in ~2010). Thanks

I bought a replacement motherboard on ebay, installed it without issue. Turned the laptop on and after an initial error message prompting me to start in normal mode (which I did), the L502x is unchanged: Powered on, the bar under the Dell logo fills all the way but then the screen goes black and a second later the whole thing restarts (Dell logo, bar fills up, black screen...on and on and on). Pressing F2 (Setup) or F12 (Boot options) doesn't work: the computer restarts before it can get to the menus.

With a new motherboard and still no fix... I must be missing something!? Any help at this point would be greatly appreciated. Thanks

What happens if you remove the hard drive from the system?

I just tried booting after removing the hard drive but same result: boot loop and can't access the bios menu. Even tried booting with the windows installer plugged in via USB stick but no luck getting anywhere with that either. Any other ideas? Thank you so much!

That would leave the memory and the CPU as the possible faulty parts, assuming the replacement mainboard was tested good (before going further, verify that with the seller).

Try one memory module at a time -- one may be bad.  Use each socket -- if one module prevents bootup in both sockets, it's bad. If both modules fail to work in one socket, the socket is bad.

If that doesn't turn up anything, the only real test for a CPU is to swap it into a known working board (or swap in a new CPU).

The replacement mainboard was tested good (has QC badge). I've tried reseating the memory modules (there are two) but no luck. Is there a way to test if they are faulty?

How do I test the CPU?

Thanks!

Tried the memory modules one at a time, both sockets. All 4 options do not fix the problem :(

I will try the CPU in another laptop (good idea?) once I have some time.

I found this video online: https://www.youtube.com/watch?v=cxu9kAZ12qI

This is EXACTLY what happens to me.The author seems to suggest that reinstalling the OS (in my case windows 10) will fix the problem. I would love to try this fix but I can't seem to boot from USB or DVD. I have tried windows 10 installation on USB and windows 7 on DVD and even with the hard drive unplugged, the computer won't boot to either USB or DVD - the same boot loop just continues. Because the boot loop is short, I cannot access the bios to change the boot order (via F2 or F12). Is there another way I'm not thinking of to force the laptop to boot from USB or DVD?

Another thought: the very last time the laptop was working before having this boot loop issue, the audio suddenly stopped working after making a weird crackely noise. I tried disabling/enabling the audio device but the audio still didn't work so I thought to simply reboot the system. I selected "reboot" from the shutdown menu and bam - I've been stuck on this short boot loop ever since.

Think it could be related to a static build-up in the speakers? Could I try unplugging them?

Let me know if you have any other ideas - I am determined to fix this laptop, it has otherwise been perfect to me :)

Thanks!

@canadian_nick  Were you able to fix this issue? any solution you can share?

I am facing the exact same issue.