Whatever credibility he once had is long gone:

“I personally feel that even if they invited witnesses and witnesses confirmed, yes, the president had a quid-pro-quo or something like this, if it doesn’t rise to the level of removal from office than why would we put the American people, the institution, through this process, when we know what the outcome is going to be at the end of the day,” Burr said.

It would take 67 votes to remove Trump from office. Republicans control 53 seats, so 20 of them would have to vote to remove Trump along with all 47 Democrats and independents.

In other words, even if he is guilty, we don't care. Understand, Richard Burr is Chairman of the Committee that has been investigating foreign interference in American elections for about two and a half years now. The President not only invited foreign interference, he demanded it, holding up military assistance that likely cost Ukrainian soldiers their lives in the process. It's no wonder Tillis has been such an embarrassment. Burr is senior, and arguably should be a mentor for the first-term (hopefully single-term) Senator. But apparently Do Nothing Burr has nothing to offer along those lines.