There is most certainly a legal or Constitutional remedy for this. The Constitution does not cover every possible contingency that could happen, which is one reason why the 10th Amendment was written - to confirm what the Declaration of Independence declares: that the default of rights reverts to the individual whose rights and powers derive from their Creator, not from man or man’s government.
The remedy doesn’t necessarily have to involve bloodshed, although it could and would be legitimized IMO by the Declaration of Independence which frames the Constitution, but only after legal means like those suggested below are exhausted.
The 10th Amendment confirms that powers not specifically delegated to the feds belong to the States and the People. The Constitution also recognizes treason as a crime. This fraud is certainly a crime and is also treason.
Therefore, a state has the right to reverse and recertify the election results if fraud is proved. After recertification by the state, the electoral vote is recounted. If the electoral vote changes in favor of the other candidate, then the other candidate (Trump) is declared President per the Constitution.
The Constitution is to be applied AS WRITTEN AND ORIGIANLLY UNDERSTOOD AND INTENDED.
- If an issue like proven fraudulent election results, is not addressed in the text, then you (or a Court) must move to original understanding of any relevant textual portion.
- If that doesn’t suffice, then you (or a Court) must move to researching original intent by the Founders and Ratifiers on the issue in question - here fraudulent election results.
Any honest inquiry with this basic understanding would be able to ratify this process knowing that the Founders and Ratifiers would not have intended fraud to carry a Presidential Election.
Thank you for clarifying the process.