That’s what the terminal in the tunnels below the hatch usually is for.
On the right hand of the terminal there should also be a place where you can interact with.
If not, check your mission counter if you already have 1/5 devices activated.
Happened for me too at 2 of 5 bases. Maybe it was Veronika.
So, finish that base or leave it alone… And Go to the next lvl3 base.
I couldn’t find any other places on the terminal to activate.
This was my first one after getting the mission. Honestly, it seems like a lot of grind, that isn’t fun 
Tried on another base Gardberg Mine Control Point - spent ~60 HEDP rockets, 20 adrenaline syringes, ~30 standard health kits because the viewport framerate is so low, killed all the shield generators, and when i found the hatch it still ha a shield on it… and while I’m waiting, the base starts regenerating, and hunters start coming out again.
This is unplayable.
Screenshots could be helpful to help you.
Maybe you’ve just overseen the 4th shield generator? 
What does the mission log say?
It should say that shield generators A,BC and D are destroyed, if they are all destroyed.
I’m not in the game any more, but it did acknowledge all the generators destroyed. This is the second time this bug has happened, where after destroying all the generators, the shield doesn’t drop over the thing in the centre (or the hatch).
I have never seen an update with as many graphics glitches as this one. Exiting to Main Menu, which usually helped, did not work and exiting and reloading was useless as well. So I abandoned it and set up my ethanol base at Brongen. I like the ethonol base there anyway, easier to cover and defend due to many containers.
My friend, if you actually had to use 20 adrenaline syringes to take just one base, then you are playing this game incorrectly. You shouldn’t even be dying once. There’s a reason why they’re called “ranged weapons”. You should be knocking these bases to pieces from long range. On many of them (but not all) you can stand off on good ground and bombard the base with the experimental Algustare (Stentorpet’s a good one for that, among others". Runnin in guns blazing just gets you shredded.
Really?? Then you never played Fallout 76.
If the hatch is still covered by the shield, then turn and walk away from the base for perhaps a minute or two. Then return and either the shield will be gone, or you have to waste the four pods again- at which point the shield should drop.
I prefer my augmented 5c RPG7.
I always take 10 rounds for it for a base assault.
8 are enough to crush most walls for a path to the shield generators and to destroy most of the turrets and spawners and the remaining 2 are enough to destroy the FNIX center.
Then you are NOT playing on guerrilla level, because that ammunition will in no way suffice for what you’re claiming on that level. The experimental Algustare is far more efficient and less costly as it uses only rifle caliber ammunition.
No, always played on skirmish.
The rpg7 doesn’t cost me anything.
All I need is loot.
But, isn’t it that way for every weapon now since the showdown update?
I usually get twice or more than I use.
I see You just wanna blow sheet up. Explains alot. In any event, the other guy’s still getting shredded by runnin in guns blazing.
No problem doing those daily “Do a Base Assault only using SMG” on guerrilla level and a level 3 base with a COM-10 and 6k 9mm FMJ. It’s not even augumented for wall destruction 
You just scout the base out and you’ll see where to start. A turret turned inward showing its fuel cells or the red fuel cells that sit on the walls sometimes is usually a good start point. Then it is important to quickly knock out spawners.
For those SMG missions I used to carry my companion to throw as a decoy if I fail with the spawners but lately I’ve become so cocky that he’s had to stay in the Plundra.
You have to go into the base genius, you can’t stay back on a hill sniping, you have to get down and pop the shields open, can’t break them from a distance. And once you do go down into the base, the lag gets so bad it’s nearly unplayable, so you’re running 10 fps while still getting shot by everything, not as simple as “stay on a hill and snipe like a coward” base defense is really bugged right now
I don’t know your system, but maybe just try at other bases? Maybe it’s location related.
For me it doesn’t lag in general at those bases.
But like I said, most of what’s there gets destroyed when I send my 8 RPG rockets into some well chosen spots. In these situations, when a rocket causes a large explosion, yes then it’s lagging for a short time.
But if it’s done, it’s done.
Another nice tactics:
Use RC ticks to open a path to each generator. You can use them over quite a large and safe distance. Then run in equipped with a jammer, open the shield generators, run out and use RC ticks or rockets to destroy the shield generators from distance.
With this there is just a small risk that you also destroy the hatch with the last shield generator.
Well of course you have to go down to the base to destroy the shields- but there’s no rule which mandates you go must down to fight every last turret and every last machine that the base sends out. Use your intellect and not your emotions. Stand off at range and reduce the base to rubble. Then move in and clean up what little is left. Of course, if you’ve spent your time charging in instead of learning to use the experimental Algustare… If that’s the case, start practicing with it. You’ll discover to your shocked surprise that the more you practice, the better you’ll become at using it.
Or, you can keep charging in and getting shredded and complaining about the Ardenaline you spent because you got you backside busted. PLAY SMART.
Yea maybe I could try a different base next time, I like to use remote ticks to clear a path and break turrets, then I use sensory jammers and put remote explosives on all the shield generators. I’m not sure if that’s better than just doing it the old fashioned way and shooting the generators, but it saves me some ammo lol
