Can you think of a way I can reset PRAM with a broken internal keyboard?

[Sharky II]

Hi all,

I have a 2012 Retina 15" MBP A1398 and it has an issue with the left shift key: it's 'stuck on' during initial booting and boots into safe mode unless you hold down other keys on start up, and then simply doesn't work when the OS is up.

Very rarely when the machine is up and running, the shift key is apparently 'stuck on' and you need to shut down etc. Right shift works. External keyboard works as expected (except on boot).

The keyboard obviously needs replacement (hopefully not the logic board - found small signs of spillage around connector area), which I'll do, but in the meantime: I want to be able to do a PRAM reset. I can't do this because when you turn the machine on, it thinks that the shift key is pressed, meaning when I think I'm doing option + cmd + P + R, it's also adding a SHIFT in there, rendering it useless.

Strangely, I can boot into recovery mode with cmd + R. Using an external keyboard doesn't let me do it, either.

I can't disconnect the internal keyboard and use the external because the power on key is on the internal keyboard.

Can anybody think of a way I can do a PRAM reset given this situation?

Thanks!

Ed
[automerge]1592603808[/automerge]
Would it be possible for me to power on the machine and then carefully disconnect the internal keyboard connector from the Logic board while the machine is running, hit restart in OSX, and then try to do a PRAM reset from the external keyboard?

Not sure you can do a PRAM reset on a reboot rather than a fresh boot, though...

Anyway, just thinking out loud!

Cheers,

Ed

 

[casperes1996]

If you don’t mind poking around inside the laptop, why not just remove the battery and wait for the capacitors to discharge?

 

[Sharky II]

Ah, good idea - yes no problem poking around. Battery connector is easily accessible

I thought that only reset the SMC (which seems to work the normal method), but I’ll give it a go cheers!

 

[casperes1996]

Ah, good idea - yes no problem poking around. Battery connector is easily accessible

I thought that only reset the SMC (which seems to work the normal method), but I’ll give it a go cheers!

It should work for PRAM as well as long as the capacitor has enough time to discharge entirely. Even the PRAM/NVRAM is still actually a form of volatile memory, it's just backed by a capacitor connected to the battery. At least on most MacBooks. There may be some that have a CMOS battery for the NVRAM.

 

[Sharky II]

That's great, thank you. Any idea if we're talking seconds/minutes/hours? Happy to leave it overnight...

 

[casperes1996]

That's great, thank you. Any idea if we're talking seconds/minutes/hours? Happy to leave it overnight...

I honestly have no idea. But it might speed it up if you, after disconnecting the battery, press the power button. It might make the capacitors discharge their residual charge in an attempt to start up. But I think you'll be on the safe side with an overnighter