Helpful tips and Troubleshoot you can use.

link for getting started setup guide for your Wireless Headset H800 : https://support.logi.com/hc/en-001/articles/360024318533

Make sure that the headset is full charged.  

If the headset battery light is blinking amber, it is not fully charged and maynot work properly.  The amber light should be 

This is common for headsets let on overnight or long periods of time, especially if the headset USB in powered by the computer and the computer was powered off

The headset should never be plugged into a wall socket and should only be charged by the device

Re-pairing the H800 headset with the wireless receiver 
You may need to re-pair your headset with its wireless receiver or pair it with a replacement receiver. Here's how:

1. Initiate the pairing mode for your headset

•    1. Remove the wireless receiver from the USB port and plug back in computer or docking station
•   2. Set the switch on your headset to the receiver icon and not the Bluetooth icon.
•   3. Slide the track switch to "Next" and hold, and press and hold the "Volume up" button at the same time, until the link LED indicator blinks rapidly.  (Green flashing light)

then 

2. Initiate the pairing mode for your wireless receiver

• Make sure your wireless receiver is connected to a USB port on your computer.
• When the headset is in pairing mode, click Next on the Pairing Utility page to initiate the pairing mode on the receiver.

Once the headset is paired to the wireless receiver, the connect LED will turn solid green and the pairing utility will state that the headset is ready to use.

Pairing the H800 headset with a Bluetooth device
To pair your wireless headset with a Bluetooth device:

1. Set the slider switch to the Bluetooth icon.
2. Slide the track switch to "Next" and hold, and press and hold the "Volume up" button at the same time, until the link LED indicator blinks rapidly.
   
   NOTE: For initial Bluetooth setup, your headset will automatically be in pairing mode.
3. Make sure Bluetooth is active on your device and then select "H800 Logitech Headset" in the Bluetooth devices list (see your Bluetooth device's documentation for more help).

Once the connection has been established, the link LED indicator should turn solid green.