Cannot reset PRAM

[minh.nkim]

Hello,

My macAir mid 2012 can only boot into Windows 10. It cannot recognize OPT to launch start-up disk menu selection.
It cannot recognize OPT-CMD-P-R to reset PRAM, thus continuously boot into Windows 10.

I tried the following, attempting to reset PRAM: --- ALL FAIL:ED ---
1. OPT-CMD-P-R with built-in keyboard
2. OPT-CMD-P-R with external USB keyboard
3. OPT to launch start-up disk selection, trying to get back into macOS then reset everything from there. Did not work
4. CMD-R to get into recovery mode
3. CMD-OPT-R, was able to launch internet recovery. Was able to download a macOS but the macOS version is not compatible with mid 2012 model. Apple support forum suggested I reset PRAM which is what I am trying now...

Would appreciate any pointer how to solve this problem: reset PRAM

Thank you
Minh

 

[chscag]

Welcome to our forums.

Are you running Windows 10 on your MacBook Air as the only operating system or are you dual booting with macOS? (like in Boot Camp)

That information is important.

Also... you're not resetting the PRAM properly. Here's how to do it:

You can reset or "zap" the PRAM on a Mac by pressing and holding the Command, Option, P, and R keys right as you turn the computer on. Yes, there are four keys you need to hold down at the same time. Once your hear the startup chime a second time, the PRAM has been reset and you can release the keys.

Notice the sequence above. Be sure to follow it exactly as shown.

 

[minh.nkim]

Welcome to our forums.

Are you running Windows 10 on your MacBook Air as the only operating system or are you dual booting with macOS? (like in Boot Camp)

That information is important.

Also... you're not resetting the PRAM properly. Here's how to do it:

You can reset or "zap" the PRAM on a Mac by pressing and holding the Command, Option, P, and R keys right as you turn the computer on. Yes, there are four keys you need to hold down at the same time. Once your hear the startup chime a second time, the PRAM has been reset and you can release the keys.

Notice the sequence above. Be sure to follow it exactly as shown.

Hello: I have the system in dual boot: macOS and Windows 10.

I held down all 4 keys CMD-OPT-P-R as soon as I turn on power. It did not work.

Thanks

 

[chscag]

Remember, you need to keep holding down all four of those keys until the machine chimes the second time. Then the PRAM has been reset. If you're doing that and it doesn't work,

Try this:

Boot into Windows. Open the Windows Control Panel Boot Camp selection. Then select macOS as the start up operating system.

If none of that works, you will need to boot your MacBook Air from an external hard drive or flash drive that has macOS installed on it. Or, if you have another Mac, you can hook them together in Target mode and boot that way.

Once you do that, you can erase the drive and reinstall macOS.

 

[Lifeisabeach]

Is it possible that your OPT and/or CMD key isn't working? Try using a USB keyboard if you have one. Or if you have only tried this using one of the two OPT or CMD keys, try again with the other. You can also test to see if the keys are working using this web browser-based checker.

 

[chscag]

Try using a USB keyboard if you have one. Or if you have only tried this using one of the two OPT or CMD keys, try again with the other.

He has already tried that according to his first post. However, you may notice as I did that the key sequence he was using was not correct. But he claims he tried the correct key sequence and it didn't work.

There is a chance that his macOS partition has been overwritten and he no longer can boot to macOS. We don't know that but it's a possibility.

 

[minh.nkim]

He has already tried that according to his first post. However, you may notice as I did that the key sequence he was using was not correct. But he claims he tried the correct key sequence and it didn't work.

There is a chance that his macOS partition has been overwritten and he no longer can boot to macOS. We don't know that but it's a possibility.

Hello again: thanks for all the help.

Indeed I tried the sequence of keys and it did not work. The possibility that my macOS partition has been overwritten is very likely. The machine can only boots Windows 10. I checked and there was no bootcamp in Windows 10, not sure what happened but looks like bootcamp was wiped out???

I have a USB boot device with macOS. I tried CMD-OPT-SHIFT-DELETE to bypass the startup drive but it did not work either.

 

[MacInWin]

Try this: Put the USB boot device in the USB port. Now power up holding down Option and hold it until you get a screen with bootable options. No other keys, and hold Opt down through the entire process. If it's working, you should see both the internal drive and the USB Boot device as options. Boot from the USB, of course, and then see if you can change the default boot drive to the macOS volume instead of the Windows.

 

[chscag]

Hi:

Try what Jake suggested above and let us know if that works for you.

And yes, it does appear that your macOS partition has either been overwritten or some how is not functioning. The fact that you have no Boot Camp option from the Windows 10 Control Panel seems to verify that.

 

[Lifeisabeach]

He has already tried that according to his first post.

*smacks forehead* I literally had to re-read that post three times before I caught it.