Decrypting the file is very easy. Go to wallet > password and enter your password in the first field only and click save. Then go to file > save copy to save a copy of the file somewhere convenient and then open it up in a plain text editor like notepad
Thanks for your tip, upon decrypted the file, the content is just what has shown on the Electrum client, with same addresses, same transactions record, but wrong keystore.
Some info:
seed_version: 17
seed_type: standard
Keystore type: bip32