Proteus may tell Sentinel to shed some of his heavier upgrades, but Sentinel puts them to good use, using his good knee to put a LOT of weight on Megatron's gut. Unfortunately, he realises that he can't get through the chest plate to his spark in his current state, but still elects to try and do as much damage as possible.

He goes for the head as well, using both hands (despite one of them being broken to hell) and pushes on Megatron's helmet, trying to get a good grip to break his neck.