I Have a 2000 Jag XK8,4.0,Convertible. I had trouble with the top Latching and Back windows would not come up. I tried all of your seguestions. Would not start after resetting Radio,I checked Battery Voltage and found it around 35%. I had drove it before this and tried the top and windows they worked fine,but I tried with voltage at 35% and Top would not latch and Rear Windows would not come up. I charged the Battery to 100% voltage and tried to raised top and windows . they both worked fine .I guess the Battery voltage needs to be nearly at full charge. I tried it many times since with the battery at high charge and the Top and rear Windows have been working fine Hope this helps some one else Thanks for all the help br549.