Oke, next steps are :
1: unlock the bootloader via the HTC dev site
2: flash a custom recovery
https://www.dropbox.com/s/yqzlpqo8illa53j/Philz recovery 5.15.9.img
https://www.dropbox.com/s/7zxfzbwewzq6hmq/twrp-recovery2.img
One of those will do the trick. Ow and remember to start always with a full battery
Then enter it and make a full nandroid backup. After this we take it further
1: unlock the bootloader via the HTC dev site
2: flash a custom recovery
https://www.dropbox.com/s/yqzlpqo8illa53j/Philz recovery 5.15.9.img
https://www.dropbox.com/s/7zxfzbwewzq6hmq/twrp-recovery2.img
One of those will do the trick. Ow and remember to start always with a full battery
Then enter it and make a full nandroid backup. After this we take it further