A command team member has posted that AO-51 might be available on holidays and weekends, I think on 435.150 downlink and 145.88 up, but if you don't hear it, don't transmit.
Here is what Drew posted on the Amsat board
We are working on this right now. There are six commands that have to be
given in sequence to make this work, and for the time being, one at the
end of a pass. It's important to shut things down to keep from damaging
the batteries even further in eclipse. There may be a small chance for a
brief recovery in the fall of this year, and we don't want to endanger
that by further harm to the batteries.
In the meantime, listen to 435.150 during the afternoon passes over the
Eastern US, especially on weekends and holidays. If you hear voices, the
repeater should be available for use with a 145.880 uplink. If you don't
hear anything, don't transmit. This is IMPORTANT: There are no promises
or predictions of when we will get the chance to run the repeater. It is
on an 'as available' basis. Please don't e-mail asking when it will be
on, unless it's for a very, very special event. If I know in advance,
I'll drop a note to here or to the AMSAT twitter account. That being
said, this afternoon is looking good.
73, Drew KO4MA
AMSAT-NA VP Operations
In the first paragraph he is referring to the possibility of a northern command station transmitting automated commands to turn the sat on.
I don't know what kind of batteries were used but since AO-51 is a sun-synchronous sat, they make have gotten baked before it started getting into eclipses a couple years ago, I doubt that AO-51 has a cooling sytem like the ISS and AO-51 is usually 2x higher or more