[Nexus 7 Android Development] BeeJ1109:
Please note:

the system partition is already quite full which leads to the problem that gapps probably will not install correctly and that may lead to weired problems (apps closing / not showing up correctly / ...). I suggest to use the dynamic gapps package linked above. In addition I suggest you to erase the system partition completely before applying the OTA package

If you get "Error 7" when trying to flash the ROM directly after upgrading to TWRP 3.4.0, wipe the Boot, System and Cache partition and clean dalvik-cache, then re-boot to Recovery and try again (you will not loose any data as long as you do not wipe the Data partition).

Some additional hints

If you are in a bootloop which shows to Google logo again and again, it's sufficient to hold vol- while booting. The next bootloop will boot into bootloader.

If you are in a bootloop which shows the ANDROID splash screen continuusly, connect your device to your PC and enter

adb reboot bootloader

After a few seconds the device should show up the bootloader screen

Hi AndSiDi

Trying to update my Tilapia, with your latest build.

I am using TWRP v3.4.0-0, as I have done several times before.

I followed your instructions, in wiping System, Cache, Dalvik-cache, as I was getting "Error 7" . Re-booted, into Recovery to install ROM again,

Tried several times, same result everytime.

Problem with wiping "Boot partition" is not available in TWRP v3.4.0-0. So that option cannot fix the issue, as suggested above.

Another issue with this suggestion, would require Root with Magisk would need to be reinstalled again.

1. Your ROM does not use "/system/addon.d" that is used to restore Magisk Root, when TWRP is flashing the update ROM, and then restores previous Magisk "modded boot.img", restoring Previous Root, without requiring a Total Magisk reinstallation, after every reflash.

All my other Devices, "Do Not require me to Reinstall Magisk ROOT" with every update.

I tried again, this time used TWRP 3.5, Which is exactly same "No Boot wipe" option.

So restored back to TWRP v3.4.0-0 as v3.5.0-9.zi is really for Android ROM 9 (LOS 16), your ROM is only v7.1.2 (LOS 14) Based.

Update:

But the install worked this time. Strange - no "Error 7".

Will now Restore Magisk Root again.

Another Update:

With latest ROM trying to Restore Magisk. Patched Boot.img.

Trying to get in Recovery Mode.

Tried Power+VolDown, hold for a long time - Nothing happens- Retried several times. Failed

Then Tried Power+VolUp Hold for LongTime - No Response should be Download Mode. Failed.

Next Tried Power+VolUp+VolDown Hold for Long Time - No Response should be Recovery Mode. Failed.

Only Power Button allows ROM to boot.

Finally trying to update Google's Play Store. That Freezes, going No Where.

Tried Clearing Cache on Google Play and Services. Does Nothing.

Cannot get into TWRP to Reflash ROM, Clear by Wiping ALL, but Internal.

Cannot use TWRP to Restore Back Previous ROM. To Start again.

Maybe I will need to get back Stock ROM, via Fastboot.

Start again.

By the way your Latest ROM, is Extremely Now SLOW. Almost as Bad as Stock.

Nothing Works on Tilapia version, some on WiFi version report is OK.

I realise difference between two, is LTE is added. That should not be a reason.

Do you have any Suggestions, I will continue to Fix it, eventually I will get sorted.

Another Update.

Found using adb command.

adb reboot recovery

Booted into TWRP to allow me to Restore, a Working ROM Previous March Release Backup, prior to Update to ROM July Release.

Found Boot partition can be Restored, using TWRP, after ROM Update, using "Magisk Rooted Boot" backup, instead of reinstalling Magisk.

EASIER SOLUTION, but would be better still to have addon option.

Cheers Beej1109.