I sent my phone to Uptrade for sale and was quoted $40. After they received it, they reduced the price to $20. This is a similar complaint by others and appears to be a common business practice.
Uptrade sent back the phone after numerous emails and I sent it to SmartphonePLUS. Within a couple of weeks, I received $44. I found SmartphonePLUS on the following marketplace:
https://www.sellcell.com/