Potty help

My mom adopted an 8 month old pekingese in December and was told by the family rehoming him that he was both crate and house trained. We don't know if he's regressed or if they just flat out lied to us but it's been a struggle on both fronts. He is as sweet as can be and so patient with my 3 year old daughter. He is finally well behaved in the crate but he is still peeing and pooping all over the house at will. They have been taking him out every 30 minutes and rewarding him if he does go outside but he doesn't seem to care. They are at their wits end and ready to give him away though it breaks my mom's heart. Her first dog ever was a pekingese and she said they never had problems like this. To add to the heartbreak, my daughter and the dog are inseparable. They became friends on day one. Help me help them all. I love the little guy too! I want him to succeed and live a long happy life with us. Thank you for any tips, tricks, advice or reassurance.