So here's the story:
Apart from my main phone, a Samsung Galaxy S21, I own three other phones by Samsung; a Galaxy A5 (2017), a Galaxy S3 Neo and the Galaxy S2 shown in this video. The first one was my main phone from 2017 to 2018 and throughout two months this year while I sent my main phone to repairs, the last ones I got from my grandmother and a friend respectively.
With these three phones, I would do some stuff concerning rooting and custom ROMs, just the stuff I wouldn't do with my main phone. However, after attempting to install an unofficial version of LineageOS 18.1 based off Android 11 onto my Galaxy S2 around a year ago, I experienced severe performance issues, which lead to me going with an older version of LineageOS (or CyanogenMod for versions pre15.0). And while doing that, I couldn't get the recovery working anymore for some reason, then I installed a foreign kernel while the original firmware by Samsung was still installed. And yeah, that is how I ended up with the phone not booting anymore.
At first, I thought that there was no hope that I could ever restore the phone, and I left the phone in a room untouched for a year. I thought about selling the phone as well, but I didn't know if anyone would actually buy it. However, I've been proven wrong now!

Music: title.wma from Windows XP.