Heist at the Sword Coast Trader's Bank

It seems we need these things:

1. The bank manager's keystone

2. The tattooed elf's keystone

3. The key to the spiral staircase (we may be able to pick this lock so this is optional)

4. A way into the building once it is shut down for the night

5. A way to disable or avoid the Detect Magic

6. A way to neutralize the Shield Guardians.

 PLAN A 
 * 1) Kidnap or neutralize the tattooed elf and steal his keystone. Then just walk into the bank and state that ownership of the box has changed and ask to be admitted.
 * 2) If more ID than simply the keystone is required, we could also either impersonate him or force him to accompany us into the bank.

 PLAN B 
 * 1) Korbo forges a note from Belinda to the bank manager requesting that he meet her somewhere and that he bring the keystone and possibly the key to the door (although we can probably pick that lock, so that might be less important). To make it less suspicious she could ask for several keystones or  something, we can discuss how to make it less fishy. Once the manager shows up we either have someone magically disguised as Belinda meet him, or have him get stood up. Either way Ma'ahni relieves him of the items we need. We could discuss replacing them with replicas if we can figure that out. Korbo might be able to fabricate a duplicate of one of the keystones if he had enough time. So then the manager wouldn't know it was missing.
 * 2) Kill the elf and take his stone? Or capture him (bound and gagged of course, filthy wizard) and get his keystone from him.
 * 3) We may be able to get this as part of phase 1, or we could just take it from his desk once we are inside the bank, or we could pick the lock. Lots of options here.
 * 4) Korbo might be able to teleport in. We could leave his beetle in the bank overnight, hiding out of sight somewhere along one of the outer walls, or better yet down in the vault area somewhere, if that is possible. Then at the opportune moment, Korbo uses places a Nomadic Anchor outside the bank (for egress). Then as an action he looks through the beetle's eyes and uses Step of a Dozen Paces as a bonus action to teleport into the bank (20 foot range). Once the goals have been achieved, he teleports out using the Nomadic Anchor.
 * 5) No idea. Some kind of magic item? Or an anti-magic shell scroll which I'm not sure we could find on short notice and also probably wouldn't be able to safely cast.
 * 6) No idea other than smashy smashy, which I think is a bad idea.

General notes and ideas:
 * Remember we have a budget of 7,500GP and the man at the flower shop seems to have some magic items, so we may be able to buy something that would help us get in. I'll start doing some research.
 * If we can find a way to become ethereal, like oil of etherealness, we might be able to solve 3, 4, 5, and 6 all in one stroke. The Shield Guardians have truesight though, which can see into the ethereal plane. So maybe not.
 * Korbo has the immovable rod. We might be able to place that at neck level in front of one of the shield guardians to pin it to the wall or something.
 * We could try to find the Shield Guardian amulet holders, or at least the control wizard. Maybe if we had control of one shield guardian, we could mess up the rotation or neglect to look in the antechambers.