One of the things I am so grateful my grandmother did was to say, from the day she was 60, that if she needed to be in a care home we (family) should make her go.
In the end she went for 2 weeks while the council were fitting a new bathroom and bedroom and then stayed long term.
Talk tot he staff, both my grandmothers were in care homes for a while and it is the staff that make the place.
My father's mother had her nails done by the staff and some came to her funeral.
My mother's mother thrived in a care home. She often didn't eat or told carers to just make her a sandwich (and fetch brandy from the shop, but that's another story ) but in the care home she was sat at a table with other people and offered a choice of hot meal.
It's horrible when a parent is upset but he needs to give it more time.
I repeat, talk to the staff, is he in the habit of getting up early? If the staff don't know his usual routine then they can't match it but if they know then they can try so if he likes to be out of bed at 6am they can help him do that.
Does he know what activities are available after quarantine? Is there something he would enjoy? My grandmother had options of wine and cheese tasting and trips out to the seaside they also had a film night.
He might have some ideas of things he'd like to take part in.
When you visit can you do a zoom meeting type look around?
Has he got his own things around him? One of my grandmothers took some furniture with her.
Check out the room, could it be set out better? One grandmother we asked to move the bed so she could see out the window (she was paralyzed from the waist down by this point).
Is he still able to do things like make a pot of tea? If he is safe to then his own kettle in his room might be an idea.
I hope your visit goes well and he is more settled.