Fight will Jill - please help

[Frost]

Today me and a Pal did the fight with Jill on Veteran Level. My Pal grabbed her while I tried to rip the electronic Device off her Chest. I know, you can shoot at it, but we tried to do it without.
We had two runs - one 30 Minutes and 60+ Minutes - but the damn thing didnt come off.
Since my Pal grabbed her every few seconds, I assume - and this is not exaggerated - I yanked at that device 120 Times.
We used up 9 Heal-Sprays, several herbs and were totally exhausted.

Is there some kind of trick or Strategy? Or do you have to shoot at that device?
Can somebody please give helpful adivce?
I cant go through this again - neither can my keyboard.

[Alien Jetstream]

Shooting at the device, preferably with the sniper rifle or the magnum, speeds up the fight by a 90%.

If you choose to tear it off with no guns, it will take forever (yeah, literally like 30 min or so).

If you shoot it with the rifle it takes around 6-8 shots, with the magnum it takes around 4-5 shots if I am not mistaken.
Of course, the risk of killing her is higher if you decide to shoot at the device but for people with ♥♥♥♥ aim like me, the sniper is perfect and is very hard to miss a shot with it.

[Skall [CZ]]

You need Damage Jill's device.
Jill's Device have: "10'000 HP"
More you damage it, more % chance to rip it Off.
You can remove device when it have below "+- 1'000 HP"