How to acces rem tech in vaults?

 That is correct, the extra "safe" "chest" "treasure" is only unlocked during the purification.  So you have to figure out how to access that spot and still make it to the door before you start purification or you will probably miss out.

That's why SAM says to check the area before activating the vault.  It's a silly and cruel thing I think. 

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@Pixeldance wrote:

That's why SAM says to check the area before activating the vault.  It's a silly and cruel thing I think. 

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Just an added puzzle to nut out ! :D

One that can be ignored by anyone who wants to.

I never that Sam was referring to looking for Rem Tech. I thought he was saying...Make sure to kill all the Rem guys in the area. Silly me 🙂

I only went out of my way once to get the tech.. I took the long loop out on the Elaaden Vault to get the tech and I won't do it again.

It was nothing really worth anything, it was just a couple containers with loot I could get through other methods. Is that how it always is? Because if so, it's much easier to just take the short route and be done with it. I was under the impression it was going to be something special but it really doesn't seem to be the case.

To answer the OP's original question, no, once the purification field has been deactivated and the vault seals up, that's it. There's no way to unseal it and go back in for loot. And as others have said, if you want all of the loot you have to get it before and during the purification process.

On a side note, could SAM be more vague when he says "I suggest you sweep the area"? Really SAM, and me without a broom!