"Action Required: Irregular activity in your AWS account." I'm unable to do anything.

Try this here to see if it help

Hello there,

I understand you are facing issues with accessing resources on your account.

Usually when this warning is triggered, the specific IAM users or even the root users are denied access to the account to prevent any further damage or abrupt charges to the account prior to confirming the account is secure.

In your case, I understand that this might be a false alarm since you have investigated and found no compromise activity.

I would recommend you do the following:

• Raise a chat contact on the same support case
• Request the connected engineer to expedite the review of your account's security as it is impacting your project

Further, the engineer will reach out to the appropriate team and have this expedited.

The dedicated team experiences high case volumes and it is the reason why they are not able to provide you a confirmed SLA. However, you can reach out to the support engineers and ask it to expedited. Please note that there is no fixed SLA for expedited requests either. The engineers will try their best to have it updated within 24 to 48 hours.

Hope I have been helpful.

Take care.