My DJI Mavic 2 Pro batteries are fat and can't install.
Why this happen and what can i do?
Please see pictures for understand.

Thanks

They are in a potentially dangerous state. Do not disassemble or recharge them and store in a safe place, preferably in a metal container away from combustible material. If they were purchased less than six months ago they should be under warranty; If you have a DJI dealer near you return them for replacement and disposal by DJI. If they are older than six months you need to purchase new ones and ask your DJI dealer to dispose of them or do it yourself safely as per your local eco-friendly requirements.

Damage like that usually happens when you don't follow the tips in this guide:

HOW TO: Maintain and store your DJI Mavic batteries

Msinger is correct.  I would follow his advice.

That hurts, how many charge cycles are on them?
The only thing I can think of is that they were run down to zero a number of times and stored/left that way??

Hi, we are deeply sorry if you are experiencing issues with your batteries. I will highly recommend you contact our support team to start up a ticket: https://www.dji.com/support. We have the professional team who would do their best to find out the reason for the problem and then the corresponding resolution would be provided.  Please note that DJI will not provide a warranty repair for cases occurring after the expiry of the warranty period; otherwise, valid charges will apply. Thank you for your understanding. Best Regards!