You are therefore back to the old system of installing the weekly ROMs. You have to make absolutely sure that your system is totally stable - restart it a few times. You will have the old version TWRP - 3.4.2b-1026 installed which does not decrypt. Do
NOT try and install the TWRP 3.5.0 separately.
To go up to this week's ROM, use the TWRP
3.4.2b-0623 TWRP.
But, DO REMEMBER - this is only for booting (temporary). DO NOT FLASH this version of TWRP.
This decrypts your data and gives access to all of the basic TWRP functions. It takes about 70 seconds to load up. You have to sign in with a pattern, not password. And you have to click a few mms beneath the target.
Use the Fastboot command:
fastboot boot TWRP_umi.img
You can install this week's ROM using the above TWRP, assuming you already have the ROM downloaded on your phone.
Once you have installed this weeks ROM - forget all of the above TWRPs. Use only the TWRP that comes with this week's ROM. Do NOT mix them.