How to clear dalvik cache if DDMS doesn't recognize device?

I have a Navon Platinum Explorer tablet (wich is not an original Navon tablet). Few years ago I was able to clear the dalvik cache, with DDMS in Eclipse (Mars) but it's full again and DDMS doesn't recognize the device, so I can't clear it. Windows says unknown device. I looked for this device in Oracle VM USB device list and there I found it as **Onda (unverified) V972 tablet in flashing mode**.
When I turn the tablet on it display the android logo and stuck there. When I press the Power + Volume up / Volume down buttons it doesn't display anything, but connects to the PC (or if already connected then disconnects). I can't enter recovery menu.
So how can I clear the dalvik cache, and disable logging so it doesn't get full again? ## From Ubuntu ## *(First, I do not really know linux yet.)*
With sudo lshw -short command I get some interesting item related to the device (with H/W path /0/100/6/*):
It's maybe possible to do something whith it?