Well, I struggled with this a lot, since caving in to updating the Apple firmware to the latest and then finding that downgrading to 5.0.2 did not let me install ATVFlash 2.5. I went through a process of elimination in trying to work out why this would not happen and the following is what I discovered.
The reboot sequence seems to be completely screwed, after jailbreak with Seas0nPass 2.4. I had not even attempted to install ATV at this stage. Decided to do a reboot instead, immediately after jailbreak and setup. Complete fail. Ended up in a boot loop.
So, I used the old Seas0nPass (2.3) which covers all the jailbreaks I wanted or needed (only two, 5.0.2 and 5.3, I cannot tether, computer and TV in different rooms) and bingo, reboot is fine. Next step… install ATV. It works, and Maintenance is installed OK. However… installing Plex still leads to a boot loop. I can’t remember how I made it comply last time I had this issue but I will get it sorted. Infuse is fine. I don’t use Kodi so can’t answer for that.
Others having similar issues may want to try jailbreaking with the older SP (its referenced on the SP pages and is needed for old firmware prior to 4.1 but is still good up to 5.3). YMMV.