2016 Ssangyong Rodius tailgate won't open

You can try pulling / pushing the tailgate at the same time as trying to open . If that fails you will have to climb into the rear , remove tailgate cover to access lock and open manually . If nothing jamming , check lock / actuator and spray with WD 40 often cures the fault

I've tried the pulling/pushing bit, I'll try the getting my 18 stone body into the boot bit later..thank you