@rosie If computer is unaccessable to you, try using a software called Kingroot. I hate to recommend it cuz it may create more problems than it solves, but it's one of the few software that can root your phone without a computer
The recent updates v2.80 & v2.81 have caused some havoc among SuperSU users. According to Chainfire and CCMT's last week announcements, they are putting 120% effort geting this done. My phone had the same problem like you guys and I fixed it by rolling it back to 2.79. I will also wait for either SuperSU v2.81 SR1 or v2.82 for a guaranteed fix.
And I also checked on permissions. The new SuperSU asked a lot of permissions. It is so because previously, it asks almost ZERO permissions. I had a look at both Chainfire & CCMT's announcements and according to them, the permissions are there because of the "feedback" option. Chainfire also dislike this option on SuperSU, and I also hope they can take it out.
If you wish to report a technical error, such as root loss and bootloop, PLEASE DO IT HERE. I will read them and compile them and sent them to Chainfire.
If you choose not to post it here. Your case will be ignored. I am putting this upfront.