You can use your hand just drop water on his nose to see if he will lick - dragons usually do not drink from a bowl - you can try a
bath as well - just do not let him start
drinking really fast or he will aspirate --- I am going to post 3 good UVB's please choose one -
For a 40 + gallon tank you want a 24" fixture
Efficient and sleek t5
UVB light fixture for reptiles terrariums and more! Order your lighting and supplies today from Pangea Reptile.
www.pangeareptile.com
this one comes w/ a 5.0 bulb you need this bulb 22"
Zoo Med ReptiSun 10.0 UVB T5 HO
or this one it can be found at Pet Smart if you have one - you want the 12% bulb 24 watt
Arcadia Reptile ProT5 UV-B Kit | reptile Light Fixtures | PetSmart
or this one you will need to replace the bulb w/ the one I posted above - 2 ft or 24" fixture
https://hydrobuilder.com/sunblaster-nanotech-t5-ho-fixture-with-6400k-lamp.html
you need two digital probe thermometers like this your pet stores carry them usually
Zoo Med Digital Thermometer
what are you using for a basking bulb? It needs to be a clear solid bright white bulb - no off white or yellowish or daytime bulbs-- once all this is corrected your dragon should start eating again -- please get this fixed as soon as possible - when you get the UVB please post back on here and I will help you get it set up for the tank - your screen on the tank will determine where it goes as well as distance