A common troubleshooting tip for the H310S Mini when the machine is either getting no power or no post can be fixed a majority of the time by reseating the CMOS battery. Here is a guide to show you how to open up the H310S and reseat the CMOS battery to fix these issues before having your machine sent in for an RMA. Simply follow these pictures to do so.
Remove the 4 screws on the back of the chassis
Pull the back panel out of the chassis, revealing the motherboard
You will want to disconnect the front panel as you will need to access the bottom of the motherboard (take note of front panel wiring for when you need to reconnect)
Remove the 4 screws holding the motherboard to the bottom panel
Flip the motherboard over to reveal the bottom of the motherboard revealing the CMOS battery
The CMOS battery is pictured here (black and red wiring with a black battery)
Simply pull the end with the white input that is connected to the motherboard out of its connection and reseat it back into the motherboard to successfully reseat the CMOS battery.
If you follow these steps correctly, this should take care of a majority of the issues that are causing no power or no post for these machines. If this does not resolve your issue, you can call helpdesk for further troubleshooting or RMA questions.