OnePlus 7 Pro: Update System Firmware on Custom ROM

Follow up to the OnePlus 7 Pro: LineageOS+MicroG post, where I mentioned I would have to update the Bluetooth & Modem firmware on my device. This fortunately went as smoothly as the LineageOS+MicroG install, so I’m very happy about that.

The first step was downloading the latest OxygenOS ZIP through this post: XDA Developers: [ROM][STOCK][FASTBOOT][OP7P] Stock Fastboot ROMs for OnePlus 7 Pro/ 7 Pro 5G by mauronofrio. The specific ZIP i pulled down from Android File Host was “10.0-GM21AA-OnePlus7ProOxygen_21.O.20_OTA_020_all_1909172051_db7a3f61-FASTBOOT.zip”. From there, it was just a simple matter of extracting that, images.zip, & flashing the bluetooth.img & modem.img files:

➜  Downloads cd 10.0-GM21AA-OnePlus7ProOxygen_21.O.20_OTA_020_all_1909172051_db7a3f61-FASTBOOT/images
➜  images file bluetooth.img
bluetooth.img: DOS/MBR boot sector, code offset 0x3c+2, OEM-ID "MSDOS5.0", Bytes/sector 4096, sectors/cluster 4, root entries 512, Media descriptor 0xf8, sectors/FAT 3, sectors/track 63, heads 255, sectors 16384 (volumes > 32 MB), serial number 0xbc614e, unlabeled, FAT (16 bit)
➜  images file modem.img
modem.img: DOS/MBR boot sector, code offset 0x3c+2, OEM-ID "MSDOS5.0", Bytes/sector 4096, sectors/cluster 4, root entries 512, Media descriptor 0xf8, sectors/FAT 10, sectors/track 63, heads 255, sectors 76800 (volumes > 32 MB), serial number 0xbc614e, unlabeled, FAT (16 bit)

➜  images adb devices
* daemon not running; starting now at tcp:5037
* daemon started successfully
List of devices attached
➜  images adb devices
List of devices attached
1234abcd        device
➜  images adb reboot bootloader
➜  images fastboot devices
1234abcd        fastboot
➜  images fastboot flash bluetooth_a bluetooth.img
Sending 'bluetooth_a' (828 KB)                     OKAY [  0.030s]
Writing 'bluetooth_a'                              OKAY [  0.005s]
Finished. Total time: 0.049s
➜  images fastboot flash bluetooth_b bluetooth.img
Sending 'bluetooth_b' (828 KB)                     OKAY [  0.032s]
Writing 'bluetooth_b'                              OKAY [  0.005s]
Finished. Total time: 0.050s
➜  images fastboot flash modem_a modem.img
Sending 'modem_a' (161700 KB)                      OKAY [  4.308s]
Writing 'modem_a'                                  OKAY [  0.633s]
Finished. Total time: 4.954s
➜  images fastboot flash modem_b modem.img
Sending 'modem_b' (161700 KB)                      OKAY [  3.769s]
Writing 'modem_b'                                  OKAY [  0.696s]
Finished. Total time: 4.480s
➜  images fastboot reboot
Rebooting                                          OKAY [  0.002s]
Finished. Total time: 0.002s
➜  images

3 thoughts on “OnePlus 7 Pro: Update System Firmware on Custom ROM

  1. I have tried this with the T-Mobile variant with no avail, would you happen to know if there is a specific modem.img for T-Mobile?

    1. I don’t believe there is a separate one for T-Mobile. I used it on my unlocked version (that actually was T-Mobile branded when I got it) but I was using Google Fi, which uses TMo towers & had no issues. It’s still just saying “No Service” after updating the modem?

      1. Yes when I flash certain modem files, but after a restart they all revert back to greying out the mobile data field in settings. I’ve checked the sim card and that works well but just not one this after installing lineageos

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