Thanks for the reply, checked the battery, while still connected it measured 8.5V which is not full, but also not really empty. Replaced it it with a new battery, unfortunately no improvement.
Lead contacts seem also no problem (meter is hardly used and looks new as well)
It's a pity, except my 2nd hand Fluke45, this is my most expensive multimeter in more than 40 years. Brymen reviews were quite good, but now I had to revert to my 30yr old Metex. It seems more reliable.
I do not know if I just have bad luck, but I am reluctant to buy a Brymen again. Schematics are not available, so troubleshooting is not easy.