In order to fix the issue, I advise you to perform a soft reset. Type *#7780# on the phone's keypad. The default lock code is 12345.
This will not delete any data from your device.
If you wish to perform a hard reset in the future and want to make sure all your data is safe, please download Nokia Suite, connect your device to it via bluetooth and go to Options > Back up.
Once the the soft reset is complete, the phone should not restart when opening "Collections".
Let us know how you get on and feel free to post any other questions you may have.
I too am facing a similar problem. The moment i try opening collections, my phone automatically shuts off and restarts. I am unable to use Whatsapp. Now, as suggested I did try to soft reset my phone but to no avail. Is there anything else i can do on my own or do i need to visit nokia service center?