I have two of these refurbished phones both power on and work fine. Issue is with the Network/Data 4G. I have tested it with T-Mobile/MetroPCS and they do not work well with the network. Do not purchase if planning to use with T-Mobile/MetroPCS. 

I would check with your carrier prior to purchase. Once again does not work on MetroPCS/T-Mobile have not tested with other carriers. Check with your Carriers 4G band numbers to ensure compatibility. I didn't so my loss is your gain. If you use the dual SIM you can not use an extra Micro SD Card. 

Copied from GSM Arena.

For Europe, Australia, Hong Kong, Singapore

NETWORKTechnologyGSM / CDMA / HSPA / LTE
2G bandsGSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2
3G bandsHSDPA 850 / 900 / 1900 / 2100
4G bands1, 3, 5, 7, 8, 28, 38, 39, 40, 41
SpeedHSPA 42.2/5.76 Mbps, LTE (3CA) Cat16 1024/150 Mbps or Cat15 800/150 Mbps (region dependant)
LAUNCHAnnounced2018, May 02
StatusAvailable. Released 2018, June 01
BODYDimensions153.2 x 71.9 x 7.9 mm (6.03 x 2.83 x 0.31 in)
Weight162 g (5.71 oz)
BuildGlass front (Gorilla Glass 5), glass back (Gorilla Glass 5), aluminum frame
SIMDual SIM (Nano-SIM, dual stand-by)
 IP68 dust/water resistant (up to 1.5m for 30 min)
MIL-STD-810G compliant*
*does not guarantee ruggedness or use in extreme conditions
DISPLAYTypeIPS LCD, HDR10
Size6.1 inches, 91.0 cm2 (~82.6% screen-to-body ratio)
Resolution1440 x 3120 pixels, 19.5:9 ratio (~564 ppi density)
ProtectionCorning Gorilla Glass 5
 Always-on display
PLATFORMOSAndroid 8.0 (Oreo), upgradable to Android 10
ChipsetQualcomm SDM845 Snapdragon 845 (10 nm)
CPUOcta-core (4x2.8 GHz Kryo 385 Gold & 4x1.7 GHz Kryo 385 Silver)
GPUAdreno 630
MEMORYCard slotmicroSD, up to 400 GB (uses SIM 2 slot)
Internal128 GB, 6 GB RAM
 UFS 2.1
MAIN CAMERADual16 MP, f/1.6, 30mm (standard), 1/3.1", 1.0µm, PDAF, Laser AF, OIS
16 MP, f/1.9, 16mm (ultrawide), 1/3.1", no AF
FeaturesLED flash, HDR, panorama
Video4K@30/60fps, 1080p@30/60fps, 720p@240fps, HDR, 24-bit/192kHz stereo sound rec.
SELFIE CAMERASingle8 MP, f/1.9, 26mm (wide)
Video1080p@60fps
SOUNDLoudspeakerYes
3.5mm jackYes
 32-bit/192kHz Hi-Res audio
COMMSWLANWi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct, DLNA
Bluetooth5.0, A2DP, LE, aptX HD
PositioningGPS, GLONASS, BDS
NFCYes
RadioFM radio
USBUSB Type-C 3.1, OTG
FEATURESSensorsFingerprint (rear-mounted), accelerometer, gyro, proximity, compass, barometer
BATTERYTypeLi-Po 3000 mAh, non-removable
Charging18W wired, QC3
Wireless (USA)
MISCColorsNew Platinum Gray, New Aurora Black, New Moroccan Blue, Raspberry Rose
ModelsLM-G710, LM-G710N, LM-G710VM, G710, SM-G710, LM-G710V
SAR EU0.24 W/kg (head)     1.47 W/kg (body)    
PriceAbout 370 EUR
TESTSPerformanceAnTuTu: 259393 (v7), 297116 (v8)
GeekBench: 8865 (v4.4), 2047 (v5.1)
GFXBench: 18fps (ES 3.1 onscreen)
DisplayContrast ratio: 2044:1 (nominal), 3.978 (sunlight)
CameraPhoto / Video
Loudspeaker-24.5 LUFS (Very good)
Audio qualityNoise -94.0dB / Crosstalk -93.0dB
Battery (old)