Macbook Pro Mid-2010 shuts down unless I hold a key down

[djbj]

Hi All,

I have just sold my old Macbook Mid-2010. It was in amazing condition, but sod's law, I installed a fresh version of Macos and turned it on one last time before shipping, and now it has developed an issue where it turns off after seeing the Apple logo, unless I hold any button on the keyboard. It turns off suddenly like a power cut. If I take my finger off of that button, it will shut off a few seconds later. I have tried the following,

- I have run a battery test and the battery is in a great condition
- I have tried pushing other buttons and get the same result where the system fully boots and stays on until I release the button.
- I have tried pushing down near the trackpad just in case it was a bad connection somewhere and it didn't have the same effect
- I have swapped out the ram (with a used ram from another macbook) but the same issue persists.
- I have swapped out the HDD (with a used HDD from another macbook) but the same issue persists.
- I have tried to boot into the HW diagnostics (hold D on startup) but it comes up with an exclamation mark with a link to apple support.
- I have cleared the SMC, NVRAM
- I have re-installed el capitan.

My next steps were,
- try to manually boot from hardware diagnostics from an external usb
- to disconnect the integrated keyboard and use an external one
- try a new set of ram
- try a new set of HDD

Is there anything else I can check? I know PCs but I'm not a mac expert.

Thanks in advance everyone

 

[Fishrrman]

Better cancel that sale and give the buyer his money back.
Selling "known bad" equipment is no way to keep your reputation in this world.

 

[rovostrov]

I would try booting into safe mode (press shift during startup) and then scan the disk using Disk Utility.