1.) Doesn't matter, just make sure you are on the latest firmware from stock.Thank you for your prompt response. May be I was not clear in asking my doubt. My point here is,
1. Do we need to be on stock rom or can come from custom rom.
2. This phone is been tricky to run around as power users without TWRP. So when you say fastboot/bootloader, do you mean to say "fastbootd" mode or regular "fastboot" mode.
Ah. Good to know.
This is the first time I've flashed a ROM like this. It has several .sig files missing. I'm guessing that's due to not being OnePlus firmware. It fails at the vendor.img though. It returns:
extracting vendor.img (1323 MB) to disk...ziparchive W 12-22 14:58:22 6940 3964 Zip: unable to truncate file to 1387766136: File too large
failed to extract 'vendor.img': I/O error
Not sure what I'm doing wrong.