It starts with 5 but the second character is F followed by other characters with two invalid Base 58 characters and checksum error which makes me understand that last four characters are not correct. So, in total the key has the atleast 7 characters wrong and could be more.
It has to start with 5H, 5J, or 5K.
The invalid checksum is telling you that the checksum is not correct for the key you entered. We already know that is the case because the key contains invalid characters. This does not necessarily mean the checksum contains errors - the checksum may very well be the correct checksum for the correct key and will validate just fine once you sort the other errors.
Appreciate your suggestions and advice.
Use btcrecover as I suggested above. If you are struggling with this, then your only option would be to ask a third party wallet recovery service to run it for you. I'd be happy to give it a shot as well, but this will necessitate you sharing your incorrect private key with either the wallet recovery service or myself.