Hi
company cannot force to complete the notice period, only it can ask you to pay as per the clauses to pay for the notice period.
The company cannot hold you and no legal steps they can come up with in terms of compensation.
If you don't want an experience letter and your new employment is secured without it, go ahead and take up the new job
make sure that you tendered your resignation letter with the date applicable.
legally they can forfeit your basic salary /gross salary. At present don't make nay offer to pay them, just hand over the company assets which are with you.