Brymen BM257s - Out of cal. (C_Er-fault)

[cs.dk]

I've got a Brymen BM257s which suddenly shows "C_Er" when powering up. The meter has not seen any sort of abuse.

From the manual;

Periodic calibration at intervals of one year is recommended to maintain meter accuracy.
Accuracy is specified for a period of one year after calibration. If self-diagnostic message “C_Er” is being displayed while powering on, some meter ranges might be largely out of specifications.
To avoid mis-leading measurements, stop using the meter and send it for re-calibration. Refer to the LIMITED WARRANTY section for obtaining warranty or repairing service.

This is second time one of my 257s' does it. The first got replaced under warranty. This one is out of warranty, is there something i can do myself? I can send it of to cal, but it will cost nearly as much as a brand new meter.
Any thoughts on DIY repair?
The meter won't measure DC volts. All other ranges seems to work.

Not first time that fault is seen;
https://www.eevblog.com/forum/testgear/brymen-257s-lost-calibration-data/