Hi Sam,
My brother recently booted his 4K+ and came to the conclusion it was still running OSMC from oct. 2020. I tried to update it with a USB stick but it now boots and then goes into a sad face bootloop. I can SSH into the machine. Is there a way to do a full format and reinstall, or any other way to fix this?
Yes that is what I did and what bricked the machine. I have tried every version available in the installer and all do the same thing.
There’s an install log written to the SD card/USB stick. Can you post what it says?
I only have dtb.img, kernel.img and filesystem.tar.xz on the stick. No log as far as I can see
I’m wondering whether the installation has started at all? You should see a warning in the beginning that the device will reformat the internal file system in a minute or so …?
Have you tried all USB ports with the stick? No other USB mass storage device should be connected while that phase.
Any chance that you can do the reinstallation with an SD card, instead?
Yes, you might do better with an SD card. Or try ‘toothpicking’ in the AV port.
Ok, I took the device home and have an SD card here, I’ll try that one 
. I’ll come back to you!
Install with the SD card succeeded on the first try.
I might mention that the PSU on this device got fried and my brother powers it through the white USB port. Maybe the USB installer doesn’t start on the black port?
Anyway, the device boots back up into Kodi, so everything is fine! thanks!
In my experience, SD cards work better than some USB sticks. Sometimes if you do a deep re-format of the install media (to FAT) before burning the install image it works better. But glad you got it working.
You can buy a new PSU here
or buy it on your own but consider the following
Power supply specifications: DC 5V, min. 2A, centre positive, coaxial power connector male with OD 5.5mm and ID 2.1mm. The connector should have spring contacts (Type ‘M’) for a reliable connection.
Don’t use chargers since they often don’t offer a stabilized voltage.
There was an old bug where the black port didn’t work around late 2020. It got fixed but that makes sense why it didn’t work.
Sam