W10 Boot Issue

A new Acer Aspire 5 laptop with it’s supplied W10 on a 125Gb SSD and Ubuntu 18.04 on a 500 Gb SSD installed in the available empty drive bay. This is my wife’s laptop and she wanted me to remove Ubuntu as she was more comfortable with W10. I removed the Ubuntu drive and was going to repair the W10 boot with a W10 repair thumb drive.

Upon trying to boot, with or without usb W10 drive inserted, this comes up instantly. No chance to hit f12 for boot source selection.

"Minimal BASH-like live editing is supported. For the first word, TAB lists possible command completions. Anywhere else, TAB lists possible device or file completions."

How can I get this thing to boot from the flash drive so I can repair the W10 boot function?

 

OK, so it looks like I've scared everyone away here by making this unnecessarily complicated. Here's the basic version of my question:

Acer Aspire 5 laptop with Windows 10 on a 125Gb SSD won’t boot up. Something happened to the MBR and on trying to boot from my Windows 10 boot repair USB drive, I do not get the moment when I can access the boot order with f-12. It acts the same with or without the thumb drive inserted.

How can I get this laptop to boot from the flash drive so I can repair the W10 boot function?