If you just want a more usable Passport today, consider sticking with BB10 and using the Android Runtime 4.3 (limited but stable) instead of a buggy Lineage port.
Step 1: The Bootloader Unlock Unlike a OnePlus or Pixel, Blackberry hates this. You must use QFIL (Qualcomm Flash Image Loader). You will download a "Firehose" programmer file. Put the Passport into EDL mode (Emergency Download) by holding Volume Down while plugging it in. Flash the unlocked aboot partition.
Step 2: Flashing TWRP Open a command prompt in your ADB folder.
adb reboot bootloader
fastboot flash recovery twrp_passport.img
fastboot reboot recovery
Step 3: Wiping the System Inside TWRP, go to Wipe > Advanced > Select Dalvik, System, Data, Cache. (Do not wipe Internal Storage if your ZIPs are stored there). Blackberry Passport Lineage Os
Step 4: Flashing Lineage Select Install > navigate to lineage-15.1-passport.zip > Swipe to confirm. Immediately after, select Add more zips > OpenGApps.zip.
Step 5: The First Boot The first boot takes 10-15 minutes. The screen will stay black then blast to the Lineage boot animation. Do not panic.
Note: This is the most critical step. Flashing the wrong radio file can brick the device. If you just want a more usable Passport
Most Android ROMs for the Passport require the device to be in a specific state. Historically, the method involves:
Standard Fastboot Method (If supported by your specific ROM):
BlackBerry locked down the Passport hard. You cannot install LineageOS without an unlocked bootloader. Step 3: Wiping the System Inside TWRP, go
Download Passport TWRP (e.g., twrp-3.2.3-0-passport.img).
In fastboot mode:
fastboot flash recovery twrp-xxxx.img
fastboot reboot
Enter recovery: hold Vol Down + Power on boot.