I had some serious intermittent issues with my Jolla after the latest update(I think, it's the update). The phone started to go to a reboot loop and I have to go for a batttery pull reset everytime. Sometimes it shut down in the middle of a process like a call or internet browsing. I was worried it's going to get bricked and even started a thread here enquiring about the same.

Taking @coderus advice, contacted Jolla care and they were very helpful. After going through their troubleshooting steps, it's all good. The issue is no longer occuring and I am so releived. Eagerly waiting for my TOHKBD2 now ..

I am sure you already have, but in case you have not, try to contact Jolla care and hopefully they can sort out your issue.