Hey, you!
Do you see that Synthetic over there?
Is it breathing? No? That means it's dead, and that you should try to fix it up!
Drag it towards the nearest Engineer, and tell them to fix them up using a BLOWTORCH and CABLE COILS, the former for brute damage and the latter for burns!
Then, drag the machine to the nearest Medic or Doctor or any person able-bodied and able-minded to efficiently and properly use the tool known as the EMERGENCY DEFIBRILLATOR. Bug them until they apply those paddles to the Synthetic and bring them to "life"!
If the Medic screams that the Synthetic is braindead, then immediately AHELP. There's a known bug in which Synthetics either cannot be defibrillated, or are stuck in limbo, between life and death (a pseudo-hardcrit if you will) even with 100% HP.
If the Medic screams that the body has no soul, then the Synthetic cannot be defibrillated, and the person playing them doesn't want to play anymore, most likely.
Keep this in mind whenever you see a broken Synthetic. Fix them up, and you'll surely be rescued and fixed up aswell by their hands, sooner or later!