He was scammed by Dennis Montgomery and a couple of other pseudo-experts. Can’t admit he was snookered.
If you read the entire story of Dennis Montgomery a lot of people knew he was a fraud and scam artist, but Lindell was so invested in the idea that the 2020 election was stolen he bought off on a fraud, as you say, he can’t back down now and admit he was scammed.
The 2020 election was fraudulent, just not in the way Lindell believes, certainly not from Chinese hackers and he had the packet captures to prove it.
Anyone with a fundamental understanding of computer networking and how someone gathers packet captures would almost immediately know his claims were a fraud.