If the Slingbox is not responding properly when you perform the Reset to Factory settings, I recommend trying a new power supply to confirm if that is the cause of this issue or if the Slingbox is not working properly and it needs to be replaced.
Regards and hope this helps.
If the Slingbox is resetting properly, but you are not getting a solid network light, I recommend trying a different Ethernet cable, maybe a different network too and confirm that you have the Slingbox hardwired to it using a regular cable, no longer than 7ft long. You also can try to perform this steps:
If you don't see flashing lights during the reset of the Slingbox, probably, a replacement of the power adapter will be the only solution. In this case, I recommend Contacting Technical Support.
The network light is not coming on at all. I already tried different network cables and switch ports.
Only thing I see, is a solid power led. When hitting the reset button, the powerled stays solid and won't start blinking.
If the power led is on, can the problem still lie with the power adapter?