DVBSky T9580 possible firmware issues?

I wonder if someone would be able to offer some advice?

I recently noticed that TVHeadend is not allowing me to scan/watch any channels on DVB-T. DVB-S is still working fine. It's a dual tuner DVBSky T9580 V3. I'm not sure when this stopped working as I had not used it for a while. I am using the LibreELEC 9.2.6 x86_64, I'm using the latest nightly of TVH 4.3, and I have tried 4.2 too.

After a LOT of googling a number of people had had the same issue with the later versions of firmware dvb-demod-si2168-b40-01.fw version B 4.0.25 and I should use version 4.0.4 to 11.

So with this information, I did the following to set an earlier version.

cd /lib/firmware

mv dvb-demod-si2168-b40-01.fw dvb-demod-si2168-b40-01.fw.old

wget dvb-demod-si2168-b40-01.fw

reboot

But after a reboot and typing 'dmesg | grep si2168' is shows that the version 25 firmware is redownloaded.

[ 6.314041] si2168 13-0064: Silicon Labs Si2168-B40 successfully identified

[ 6.314045] si2168 13-0064: firmware version: B 4.0.2

[ 9.888887] si2168 13-0064: downloading firmware from file 'dvb-demod-si2168-b40-01.fw'

[ 14.204480] si2168 13-0064: firmware version: B 4.0.25

[ 14.301389] si2168 13-0064: downloading firmware from file 'dvb-demod-si2168-b40-01.fw'

[ 18.703310] si2168 13-0064: firmware version: B 4.0.25

Can anyone offer some advice on forcing earlier firmware versions from 4.0.4 to 4.0.11 and NOT 25?

Thanks.

Quote from CvH

the firmware folder is /storage/.config/firmware/

There is a wiki how to do it.

Add Firmware - LibreELEC.wiki

after reboot you should see a different version

Thank you! With your instructions, it's now finding some services using downgraded 4.0.11 firmware.

Although oddly some of the Freeview transponders are not returning anything, so I guess I'll try a few different firmwares, has anyone else got issues with some of the frequencies?