You need to get care and diet correct first.I want to save the other tortoise at least .. Other than care how can I diagnose early disease ?
A 4' x 8' (1.5 x 2.2 metres) enclosure.
Torts are not social. They fight and bully. They need to be kept alone.
There needs to be a water dish - a terracotta plant saucer is great - available constantly
The substrate of the enclosure must be earth or compost and not sand. Sand sticks to food and impacts in the gut.
Use a flat piece of rock or slate as a food plate.
Feed as wide a variety of leafy greens as possible. No fruit, tomato, bell pepper or carrot.
Sprinkle a tiny pinch of calcium powder or finely ground eggshell on food three times a week.
Make sure your tort has constant access to basking in direct sun or under a lamp by day.
Make sure your tort gets outside for an hour at least 3 days a week or has a UVB lamp.
When the weather is very hot, your tort must also have access to deep shade.
Soak your tortoise for at least 30 minutes every day.
If you get all that correct then you are looking for steady weight gain and a healthy appetite. A tort should feel heavy for its size.