2 Dell Latitude 3510 stuck in Dell logo. BIOS needed.

First laptop:
Dell Latitude 3510
ST: 7YRG463
MB: MOCKINGBIRD-L CML UMA 6L 19746-1
Core i3

Second laptop:
Dell Latitude 3510
ST: 4GTG463
MB: MOCKINGBIRD-L CML UMA 6L 19746-1
Core i3

Thank you in advance....