Did exactly what NavyLCDR said above and it's working again! Thank you everyone for helping me out, really appreciate! :D

I'm finally back home. So, I created a 100mb FAT 32 partition on Disk 1, assigned the letter S and named it EFI with "Partition Tool", was about to use DiskPart to tranfers boot data to this new...

Thank you everyone for the help. Unfortunately, I'm not at home right now, so I can't try the fixes you guys recommended, but I expect to be back home tomorrow and will be trying them out.

It's...

Ok, I set BIOS config to default (I changed boot option to "UEFI only" to load the usb with Windows installer before installing it) and HDAis showing now. I don't know if that was really the...

Maybe I installed Windows 10 on HBA while HDB was pluggued, could be the reason why boot files ended up there, but I can't be sure. The strange part is that after Windows 10 was intalled on HBA I am...

No, I didn't. I thought that whatever Windows partition was there was from the old Windows installation I had in that drive a long time ago. I did "look" at it on "Computer" after formatting and it...

So, here is my problem:
I tried to install Ubuntu 16.04.3 LTS to an old HDD I have (let's call it HDB) while maintaining my main OS (Windows 10) on my main HDD (let's call it HDA). The problem is...