I'd try "dropping" the firmware version down to 14.2 as lots of folks have trouble with 15.2 behaving well on their PB360s.
It was thanks to my efforts to use 15.2 that I learned all about hard resets...
In fact, I can't find version 15.2 for download for the PB360 on either the Pocketbook.reader.com site or the Pocketbook-Global-USA site. It's just not on the official sites.
Now that you've hard reset it - maybe 14.2 will work for you.
Marilyn