Exclamation [Q] Cancelling In-Progress OTA Updates?

Hello, all!

I'm wondering, how do you cancel an OTA update once it has started? I mean after it has downloaded, and you have chosen to install it.

Here's my problem: Everyone talks about how running an OTA update unroots your phone. No problem, I can just re-root it. What no one talks about (at least I didn't run across it before doing this) is installing OTA updates when you have TWRP installed...

So, my phone downloaded the update, and it asked me to install it. I accepted, it restarted, and TWRP came up. From there, nothing happened. I tried restarting it, and it booted up just fine. After about a minute of being up, the "Phone is shutting down" (or something along those lines) message pops up, and it reboots again.

I'm wondering, how do I go about cancelling the update? I've read online I need to download the update manually and run it through TWRP, but until I learn how to do that (and spend a few hours downloading it on this freaking slow internet connection), I would like to be able to use my phone.

Another alternative that I don't know whether is possible, can I somehow use TWRP to browse to where the OTA update was downloaded to, and install it through there? If so, what would the procedure be for doing so?