I think once it reaches the SCOTUS, Trump will be declared the winner.
The US Supreme Court does not have the power to overturn the votes of the states.
Bush v Gore in 2000 - the Supreme Court pointed out that their decision was not a precedent on future election issues. It decide one narrow point - could the Democrats require the Florida Secretary of State to wait to certify the electors and vote totals past the state legislature set deadlines (to allow additional recounts). The answer was no.
In 2000, Florida was one of the earliest states to certify the popular vote. The Secretary of State later had to submit a corrected certificate, but it was submitted on time.
At most the Supreme Court could say a state has violated federal election law in denying VOTERS rights. Candidates such as Trump have NO rights unless granted by the state legislature. At best, they can get orders to allow Republican voters whose ballots were disqualified to challenge the disqualifications.
Because of the Electoral College deadlines, the best the Trump Team could hope for is to have one or two states which voted for Biden have their Electoral College votes thrown out. The state and their voters will be not represented in the official vote for President.
Here is a key point from the 12th Amendement
The person having the greatest number of votes for President, shall be the President, if such number be a majority of the whole number of Electors appointed
(source - https://www.archives.gov/founding-docs/amendments-11-27
Say the PA slate of electors is challenged and the 20 electors and their votes are thrown out. That means only 259 electoral votes are needed to become President.
And the NEW House and Senate have the sole power to decide to accept or reject the electoral votes of a state - NOT SCOTUS.
In 1960 - the State of Hawaii submitted two sets of elector / electoral vote certificates. The Republican electors and their votes were thrown out, and the Democrat electors and their votes were accepted BY CONGRESS. https://en.wikipedia.org/wiki/1960_United_States_presidential_election_in_Hawaii
Does he have any restrictions to avoid going nuts knowing he’s out?
No. He is still President. But for many things he needs the help of Congress, and very few would support him on anything crazy. There are even checks which would stop him from launching nukes without a credible threat.
Why did maine elect a republican senator but biden for president?
Because the people of Maine apparently like the way their Senator has been doing things for them. Tip O'Neill supposedly said "All politics is local"
Votes for an incumbent that has a staff that works hard to help the members of their state/ district are very common. Doing that job is much more important than party to most voters.
In Texas a moderate Democrat flipped a House seat in 2018 when the existing Republican retired. The district is overwhelmingly Republican. Yet, this Democrat was re-elected by a wide margin. One of the things he was instrumental in accomplishing this year was to get a major hospital owner in the DFW area to donate an excess building to the VA, and the VA to accept and start to staff the donation. That is taking care of the local people.