Doro 810 factory reset - Doro Lands Phones

Hold the #button to toggle the off and on switch from silent mode but if stuck pls go to factory settings and all will be fine

Try backing up your phone then do a factory reset.

talk with a phone shop IT specialist but generally if you reset using the factory reset system that cleans a phone up to the point where your log in details will still prevent it from being used

Reset it to factory settings.

Maybe a hard reset.. read about it first; you may not want to try it.

https://phones.brain-start.tech/hard-reset/how-to-hard-reset-your-doro-phoneeasy-508/

Follow the instructions on the screen to set up your phone and prepare it for use.

1. Find "Reset all" Press the Navigation key. Select Settings. Select Security. ...
2. Restore factory default settings. Key in the phone lock code (default is 1234) and press the Navigation key. Press the Navigation key to confirm.

Doro 6520 - Restore factory default settings - Device Guides

https://userguide.vodafone.co.nz/doro/6520...os/basic.../restore-factory-default-settings/.
or go to this link might help.
How to reset clock on 6520 mobile Google Search

Try to master/factory reset and see it is working. If it don't, you need to hand it over to a skilled professional

goto this wepage put in your model number and you can download your replacement manual.
http://www.doro.com/global/businessunit/dorohome/support/manuals

Reset base unit defaults
Resetting will return most functions to the original factory default setting.
Registrations are not affected by resetting.
1. Press Menu.
2. Scroll using v/V to Base Set. Press OK.
3. Scroll using v/V to Default Set. Press OK.
4. Enter your current base unit PIN code (0000 at default).
5. Press OK to confirm.

Hi,
Well, I'm sorry to say that I've spent the last hour trying to find a way for you to reset this to factory & it looks like you can not. I had a hard time believing that (which is why it became an obsession) but, I think you're going to have to ask a neighbor to record a message for you. Actually, that sounds like fun :-)
Good luck.

remove the RAM. boot minimal only (floppy). get to BIOS screen. reset to factory default. try again with boot floppy. if ok, re-install RAM and repeat