Dear @Divy Valji,
Thank you for your update. It was really helpful.
Since your admin is having trouble signing in the admin account, may I ask if they are the only admin available or there are other admins that could help him with the MFA reset/revoke following this article: Manage user authentication options?
If your admin is the only admin, they would need to contact Data Protection Team to help regain access for the admin account.
Please note that I have no control over user accounts, especially when it comes to logging in to your account, resetting your password, changing your access, etc.
Please try to find the related hotline number to call the frontline let them raise a ticket for you: Customer service phone numbers - Microsoft Support (Scroll down for Business users)

In some countries, this is an automated conversation: First, when you call the hotline, they will ask you what kind of problem you are struggling with.
Answer: Authenticator.
A: What products do you use?
B: Office 365 for business.
Verification: Education or company account?
B: For companies
A: Are you an administrator?
B: Yes.
A: Are there any other administrators in your organization?
B: No.
A: I need one.... Service request?
B: Yes
(Important Note: Sometimes, you would hear the computer-generated voice at first, please kindly wait for it to end, and if an agent is available, you would be directed to them and get your support. Depending on your country or region, when you call the support number, you may hear an introduction of about 30 seconds such as "You can visit the link...". You can ignore this introduction and wait until you are presented with the options. Then press "1" as a business email user, and again "1" for technical help.)
As an alternative, your admin can create a new tenant account and submit the request from there.
To set up a new tenant, please follow these steps:
Once the new tenant is created, your admin should be able to access the support portal and submit the ticket referencing their locked account without further issues.
In the ticket's description, they could refer to this message "Hello,
I am currently locked out of my Microsoft 365 tenant because multi-factor authentication is enforced, and I am unable to complete the verification process. I am the only global administrator for this tenant, which means I cannot access my account or the Microsoft 365 Admin Center.
To resolve this, I have created a new tenant and would like to be connected with the Data Protection Team to verify my identity and assist with regaining access. I am available to provide any required documentation or verification to support the recovery process."
Ticket Support: Log in the Microsoft 365 Admin Center using the newly created trial admin account > Support > Help & Support. Your admin can raise support ticket at: https://admin.microsoft.com/#/support/requests
For more details, you could refer to this article: Get support for Microsoft 365 for business
Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.
Kindly let me know when there are updates or if you need further assistance. Any updates you’re able to share would be really helpful.
I'm here and happy to help! Thank you for your kindness and patience!