Laptop stuck in "shutting down..." after "configuring updates"

Note: I can't take any screen shots because my problematic laptop won't even start up fully.

So as a bit of background, my 6-year-old Toshiba A505-S6005 laptop battery has been horrible for ages (as in my laptop MUST be plugged in at all times or else it will immediately spontaneously turn off without a proper shut-down. It also spontaneously turns off it it overheats or starts working too hard or something), so I don't use it very much - but it's where I keep all my music and movies, and I've been gradually transferring these files to other devices, which is why I still use it occasionally...

Anyway, 2 nights ago, I downloaded and installed updates, and after taking a while to install updates, it stayed on the "shutting down..." screen for a long time... And when I woke up the next morning, it was STILL on the "shutting down" screen - and it had been 8 hours by that point (I was actually very surprised that it hadn't spontaneously turned off overnight). So I did a force-turn-off because I thought it would start up ok.

Today, I turned on the computer figuring it would boot up ok. So we get to the start-up screen - it even spends a mere split second on the usual improper-shut-down-how-would-you-like-to-start-up screen (it usually spends 30 seconds on that screen) and it goes through "configuring updates," and this took a while, and then it went back to the "shutting down..." screen. And it was stuck there for about 20 minutes before I did another force-turn-off, and turned it on again because sometimes something that doesn't work one time does indeed work the next time. But not this time. It went through the same "configuring updates" and "shutting down..." screens, and it's now been stuck on "shutting down..." for about 30 minutes.

So, what can I do to fix it? I can't figure out how to get it to fully boot up, because paragraph #3 above just happens over and over again. Will I have to take out the hard drive and finally retire my computer? Would I be able to take out the hard drive and recover my files?

Thank you!