

Google:
Acer Aspire a315-23 factory reset bios
There’s a bunch of videos and guides, just need to find one that matches your computer. Usually hit a button during startup to access to BIOS and can reset from a menu there.
Terminal would be after startup, more operating system level stuff.
Nothing permanent that I can think of. You’re probably running on mostly default settings anyway. It’s a laptop so you’ll likely only have one hard drive so boot order shouldn’t be an issue. Only thing I can think of is if you got some kinda hardware encryption setup, but that’s not likely on your typical laptop.