Iam in same situation as yours... I tried to update my android phone around 1:15pm and it is still " Installing system update..." and now it is 2:00pm.
How can I reboot with out losing information? How long it will take to complete ? Do I need to wait to complete ?
To the above members: The reported delay to update
is buggy. As pointed out above it shouldn't take more
than 20-30 mins. Please reported to your carrier
or wait for some..Techy member explanations
Yesterday my mobile shows Android upgrading signal & I have started software update on samsung J5 prime mobile yesterday 10:30 Pm.. mobile is not yet started .... I could see the status "Android is Upgrading... Preparing Device Test..." in the display.. Please suggest me to solve this issue.
Welcome to Android Central! If it still shows it's updating, then something went wrong with the update process. Force a shutdown by pressing and holding Power and Vol Down for about 20 seconds. Then boot into Recovery Mode and wipe the cache partition: https://www.hardreset.info/devices/samsung/samsung-galaxy-m30/recovery-mode/
After that, reboot the phone and try the system update again.