There was effectively no Senate trial, because Republicans refused to call witnesses. It was a sham. If Trump was innocent, they would have been happy to call witnesses, but they exercised raw power to make it go away. To me, that constitutes “undermining our democratic institutions”.
You're referring to the impeachment process, the basis for which was a shady phone call during which Trump pressured the Ukrainian president to open an investigation of Joe Biden. That had absolutely nothing to do with the Russian Collusion investigation.
