Facing a Three-Month Notice Period but Need to Join a New Job in 30 Days—What Are My Options?

I am working in an MNC. I got a government job, so I resigned. I told the exact reason for leaving, but after a week, I realized that it was a mistake, so I took back my resignation. Now, again, I got a way better government job, and I want to resign again, but here I have a three-month notice period, and there I have to join within 30 days. I am pretty sure my manager will not accept my resignation. What should I do? Will absconding be the only option?

In my joining letter, it is written that any request from an employee for release earlier than 3 months will be solely at the discretion of the concerned manager. The shortfall in such notice period shall be recovered from the salary, subject to the decision of the manager.