Zgemma H9 combo open ATV

Hi i have two H9 combo s both running atv 6.4 working fine went to update them to 7xxx all of them but having problems with channel switching some times have to go back and forward to open them on freesat and iptv the same and 0 button recall I use only works sometimes but on 6.4 works perfect on everything tried the 7xxx on octagon sf8008 4k and it works perfect any suggestions thanks

Ok I will give it a go and update you when I try it thanks

Hi thanks for your very detailed guide I have followed your instructions the best I can not sure if I'm doing something wrong I done a clean install no back ups tried it with 7.51 also 7.6 but no joy channel switching still hit and miss some times when I change channel it just has black screen with sound then I go back in and out of it it's fine also still same problem with the 0 recall but tried it a few times with no joy so reverted back to 6.4 everything perfect smooth channel changing 0 recall button 100percent strange