when i did mine instead of rounding it the head sheared off!! even with just the tapered pin being siezed hamering it with a punch did nothing, so i got a thin G clamp in there to press it out {as it has no head and thread }even with the biggest g clamp at max force it still wouldnt come out infact at one point i thought it came out but it actualy broke the G clamp, got the blow torch on it and sprayed some oil in there and it pressed out with another G clamp,
my advice, heat it up with a blow torch but be realy careful as the heat will spread quickly to the outside edge of the door and flake off ya paint {ask me how i know} so get some one else to constantly cool the outside edge of the door with water from a garden hose, if your lucky you can rescue your chewed up torx head by hammering in a 12 point bit, there similar to torx but there great for that situation,good luck! there mine was a fkn nightmare!!