As mentioned, this looks like the no-name generic VFDs sold by many Chinese vendors. Not sure on the name, as I have seen numerous listings that look identical. I would be concerned that the units nameplate/programmed voltage and phase, that both input and output are correct for your application before hooking it up.
It is unlikely for modern electrolytic capacitors to go bad after sitting on the shelf (or in equipment) for a year or two, providing it is not exposed to high heat. Usually electrolytic capacitors that are old (many years to decades), can be checked for leakage, and/or the voltage is applied slowly monitoring the capacitors (i.e. reforming). As for mounted capacitors in a VFD, this link
http://machinedesign.com/motorsdrives/feed-your-vfd-right-power suggests reforming the capacitors by applying voltage to the VFD for 8 hours with no motor attached (i.e. no load). It is acceptable to power-up the VFD with no motor attached, just don't operate the motor controls. If power is applied to a VFD and there is any problem at start up or running, most modern units will provide an error message on the display screen. There is also a run time counter "Life Check Monitor" on some VFD models, as all electrolytic capacitors have a finite use lifespan which is dependent on % load and temperature (something like 10 years at 100% load at 30C)
If I recall, one needs a special multimeter or scope-meter to evaluate VFD outputs because of the higher carrier frequency and the signal is chopped. In this case if the unit powers up fine, I would let it stand powered for 6-8 hours at 0 Hz. Then I would try it to operate the motor. The VFDs Jim mentioned all are very good units, but it is worth reading up on specific models and features. The sensorless vector mode adds a lot to the motor control. I recently switched to Hitachi WJ200 units, they are commonly used and considered fairly bullet proof. I have also heard good things about the Teco VFDs, but varies with models. Yaskawa VFDs are top of the line, and you pay for it. A lot also has to do with the VFD features, programming, a readable manual and support.
Mark
