hi if you squeese the handle put your head near the badge you should hear 1 micro switch operating the window and a noise like well hard to explain but its a solenoid operating the rear latch after the window drops,you can get the inside panel off bit hard with door locked,at bottom of door panel is 4 philips screws take them out and then the panel pulls from the bottom up,cut round water shredder and you can operate latch manually to get it open then check to see if micro switch in handle is working its not a rear wiper fault or window fault as they work,the relay for the rear door latch and the rear window are behind the offside rear quarter panel 3 connectors for rear door electrics,the relays are up by the seat at top,its not normally a relay issue either rear door latch solenoid,or micro switch in back handle but rule out the handle as window works hope this helps
This is a previous post from Tigapiglet with regard a rear tailgate not working, give his ideas a try.
Zippy