Repetier server raspberry pi image V14 won't boot after sudo apt upgrade
I am new to raspberry pi and linux. I recently bought the latest raspberry pi 3B+ and installed the repetier server image V14 on it using a windows system on a 8GB sd card. Then I followed the below procedure:
Connect the raspberry pi internet via Ethernet and boot it up this SD card via SSH ----- It booted.
Expand file system using raspi-config ----- ok.
Reboot the pi. ------ ok
From my computer (which is connected to the same LAN) and access http://192.168.x.xx:3344 ------- Ok, the reteptier front end shows up with the start trail page.
I don’t activate the trail or do anything in the front end. I then return to the pi via SSH and perform sudo apt update ------ it takes about 15 minutes and is done.
I then perform sudo apt upgrade ------ it says there are 24 packages to upgrade and takes about 6 hours.
I then try to reboot it and the raspberry pi doesnt not boot (the act light doesn’t come on).
I remove the SD card, erase it and start with a fresh install of the repetier server image V14 and repeat the process. I get the same result at step 7.
Do you have any idea why this happens? Am I not supposed to upgrade the V14 image?
Thank you very much for you time.