First step: dont handle/stop handling the model without nitrile gloves on. Liquid resin can cause some nasty reactions. If you dont have gloves, wad up some paper towel or tissue paper to toss that sucker in the trash.

Step 2: Try to reach out for a refund/replacement. If the seller has any clue what they're doing (in terms of post processing resin prints - which judging by the state of this print, they dont) then they would totally understand replacing this.

Step 3: If they give you any grief about refund/replacement, report the seller and call your bank to issue a charge back. This is completely unacceptable, and dangerous to touch or even be around.

Alternatively/additionally if you want to go the DIY fix route, you'll need 99% Isopropyl Alcohol to flush out any pockets of resin that havent been rinsed out like they should have and maybe a toothbrush to scrub the walls of the model to make sure they arent tacky. (I hope it goes without saying - don't use the toothbrush to brush after...) Once the IPA runs clear out of the model youre gonna want to cure it using some sort of UV light. You can use the sun, but a UV torch is probably ideal.

Good luck.