Back up all phone data and remove any microSD cards.

A: There is no official 8.85 for the RM-709. If your phone says this, it is a custom firmware (modded) which is unstable. Use this guide to downgrade back to 8.75.

If you want, I can search for specific download links and a step-by-step flashing guide for your X2-01 RM variant — tell me your RM/product code (from under the battery) or confirm you want me to look up likely sources.