Restoring OEM firmware on FRITZ!Box 7530

I installed OpenWrt on my FRITZ!Box 7530 but now I want to go back to the OEM firmware (FRITZ!OS). Unfortunately, I did not make a backup before installing OpenWrt. I was thinking about doing the following on the FTP of the bootloader, but I am worried about potentially bricking the device:

quote USER adam2
quote PASS adam2
quote SETENV linux_fs_start 0
put /path/to/oem-kernel.bin mtd1
put /path/to/oem-filesystem.bin mtd0
quote REBOOT

Has anyone done this transition before? Do you think flashing the OEM filesystem and kernel is a good idea?

I also have to say that I cannot use the recovery tool because it fails with an error "The device contains basic settings adapted for your Internet Service Provider" and my ISP was not willing to cooperate. Also, I've seen reports from other users around here that even with default settings the recovery tool fails with an "incompatible memory layout" error.

AVM's recovery tool should work after unbranding the device (SETENV firmware_version …).

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Thanks for the quick reply, @slh, it pointed me in the right direction! Here is the complete solution of how to restore the OEM firmware if recovery tool fails because your router has been customised by your ISP (in my case this is Zen in the UK):

  1. Set your IP to 192.168.178.x/24 (where x is not 1) and the default gateway to

  2. Turn off your router, ensure your PC is connected to LAN1 via Ethernet, and turn the router back on.

  3. Wait for the interface to become active (usually indicated by LEDs on your PC's Ethernet port) and connect to the bootloader's FTP server, e.g. ftp -n

  4. Then issue the following set of commands:

    quote USER adam2
    quote PASS adam2
    quote SETENV firmware_version avm
    quote UNSETENV provider

    Not sure if it's necessary to change the firmware_version variable.

  5. Run the recovery tool, but make sure you do not reset the device. Otherwise the environment variables will go back to their default values. Even if the recovery tool asks you to power cycle the device, do not do it.

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