Bluetooth not working In Galaxy A50

Thank you for contacting Samsung 

first we are sorry for this bad experience 

for the problems you faced 
heating issue :
kindly Do the following when the device heats up:
- Keep the device updated with the latest software.
- Conflicts between running apps may cause the device to heat up. Restart the device.
- Deactivate the Wi-Fi, GPS, and Bluetooth features when not using them.
- Close apps that increase battery consumption or that run in the background when
not in use.
- Delete unnecessary files or unused apps.
- Decrease the screen brightness.
- If the device overheats or feels hot for a prolonged period, do not use it for a while. If
the device continues to overheat, contact a Samsung Service Center

.https://www.samsung.com/sa_en/offer/service-centers/
and for the slow device kindly follow the below :
Quick optimization
The Quick Optimization feature improves your phone's performance by identifying apps that use excessive battery power. It also clears away unneeded items from memory, deletes unnecessary files, and closes apps running in the background. Optimizing your phone is quick and simple.
From Settings, swipe to and tap Device care. Tap Optimize now, and then tap Done.
Clean storage
From Settings, swipe to and tap Device care. 
Tap on a category that has items you'd like to remove.
Tap the circles to place a checkmark next to the items you'd like to delete. You can choose as many as you'd like.
Tap Delete when you've selected everything, then tap Delete again on the confirmation
Clean memory
From Settings, swipe to and tap Device care. Tap Memory, and then tap Clean now to free up memory by stopping background apps.
You can tap Select apps to exclude and add apps to the list if you'd like to keep certain apps running in the background and
for the Bluetooth issue
ensure that the device you wish to connect with is ready to be scanned or connected
also ensure that your device and the other Bluetooth device are within the maximum Bluetooth range 10 m
you can also follow the steps: setting-tap connections - tap the Bluetooth switch to re-activate it 
you can reset the network settings by the following steps : settings-general management -reset -reset the network settings                                                                                                 

    and if you still face the same issues kindly visit the nearest service center                 
  https://www.samsung.com/sa_en/offer/service-centers/