About the phone: Huawei P9 lite VNS-L21C432B161 (Central Europe)
A long time ago, I unlocked the boot loader and managed to root the phone. I've disabled the OEM unlock option in the settings after rooting because someone said I had to do it for security reasons. Then came EMUI 5 OTA. It is somehow updated without me accepting it. Android nougat detected that the bootloader was unlocked and so it assumed that the OEM unlock option was also turned on while it was really not, which made me prevented from reactivating it.
I've used the https://forum.xda-developers.com/huawei-p9lite/how-to/tutorial-rollback-n-to-mm-c432-devices-t3563955432-devices-t3563955 "<- Official restore package and installed ROM stock by Dload.
This is the part where I planted myself horribly
Now, I wanted to update Android 7 again, but Updater did not give it to me and I could not get it through TWRP. I've reinstalled the cancel package in download mode because it allows to add any ROM, hoping to then install Android 7 in download mode. ROM.
Now I'm stuck on the "Your device has been unlocked and can not be trusted anymore. TWRP 3.0.1 must be installed but it never starts. Unable to access the boot loader, the phone does not seem to detect the power + volume reduction combination. Recovery remains stuck on the shortest warning screen at startup, recovery is also clogged. It was like that even before I tried, I do not know what caused it. I can not even access the download mode, which remains stuck also on the screen shorter warning.
Objective: to get to the boot loader without using the volume keys (this just does not work for any reason) and without going into system / recovery / erecovery because they also broke.
Thanks in advance