Need Source for Replacement Motherboard - Vostro 3520

My Dell Vostro 3520 <Private data removed from public view. DELL Admin> ( i7-1255U) has motherboard issues. It was having constant BSODs, even during reformatting. A legitimate, authorized (non-Dell) repair shop diagnosed it as a definitive motherboard failure.

I am now looking to buy a new or refurbished replacement motherboard but cannot find a source. Local stores don't have it.

If anyone in the community knows a reputable source or has a link to where I can purchase this specific motherboard, it would be a huge help. Thank you.