Use the older image -
When I said it didn't work it was the apt-get purge unattended-upgrades.
You can do apt-get update followed by apt-get upgrade , but apt-get upgrade may install some updates that are not needed. (Your call.)
Got it, I'll do it by gui.
1. Power problems.
The recommended power supply for a 3B+ is 2.5 Amps. Use a short USB cable (25cm). If needed, use an AC extention cord. Using a USB powered hard drive with an R-PI, and a weak power supply or a long USB cable, is a recipe for problems. When the R-PI is up, scrool through the output of dmesg. If you see "undervoltage" you have a power problem.
The power supply I'm using is 5V----3A
2. SD-card
Using a good quality SD-card is important. Generic cards are known to cause problems. Also, even if new, all SD-cards should be reformatted with SD Card formatter and tested with a utility like h2testw1.4 , before being flashed with Etcher.
3. Image
Always run an MD5 hash check on the image before using it.
I get a new SD CARD from Samsung. 32 GB, UHD 3, Class 10.
I use balenaEtcher, it does a check at the end