A:AnswerIt will only work w/ the S5 if you have a wireless charging replacement cover that Samsung offered. If you have the one that came w/ the phone, then you do not have wireless charging capabilities on your phone.
A:AnswerDebz, typically all wireless chargers will charge a phone as long as that phone accepts wireless charging. To find this out you could contact the manufacturer (LG in your case) or search Google for "LG V20 wireless charging". I searched and attached a response from LG, it looks like you would need a specific case made to accept wireless charging.
https://www.google.com/amp/s/forum.xda-developers.com/v20/how-to/lg-v20-wireless-charging-support-t3486488/amp/
A:AnswerA Samsung associate in the store told me, "the only difference with these two is you have your phone lying flat on one and standing or lying on it's side on the other".
A:AnswerFlashing light I believe means it's not connected correctly. When this happens to me I just take it off the charger, wait for the light to stop and replace it on the charger again. Solid light means it's working. Thanks.