Chosen Solution
I bought this MacBook Pro used. Everything was great except the keyboard which had some signs of water damage (it pressed random keys, some keys weren’t working, it double typed). So I decided to clean out the keyboard and whole laptop. Before the disassembly, I messed around with Bootcamp (not sure if it’s important). Everything went great, but the backlight film had a big coffee stain on it. Anyways I took out the keyboard and put it into my ultrasonic cleaner filled with distilled water. It spent there like 2 hours and then it was drying for like 7 hours. I made sure that the keyboard was fully dry. I reassembled everything together. When I turned my system on, it showed a white screen (no chime) and went to this screen “No bootable device — insert boot disk and press any key“ keyboard was not responding except the power button. I tried holding the alt key, resetting PRAM, SMC, but nothing worked. I took out the hard drive but still, it is showing this. It appears that the machine is stuck in some sort of BIOS mode or something. Is there anything that I can try before replacing the keyboard? Also, the external keyboard does not work either.
Sadly I think you did your self in when you used the ultrasonic cleaner on the keyboard. Water tends to find its way in to the contact areas so unless you pull the keyboard assembly apart you really can’t clean it using an ultrasonic. So you will need to replace it MacBook Pro 15" Unibody (Mid 2009-Mid 2012) Keyboard Your systems boot volume got messed up which is your other problem. You’ll need to use another Mac to rebuild the drive with macOS Sierra (10.12.6) Using your other Mac reformat the drive with GUID and a journaled file system. Download the OS from here: How to get old versions of macOS and follow this guide How to create a bootable macOS Sierra installer drive Start with this release and if you want upgrade to Mojave which is the highest version your system will support.
