Multiple Streak 7 Issues - any diagnostics or suggestions?

I have had my WI-FI only Streak 7 for about 2 weeks now and I cannot figure out what is going on with this device.  Here are just 3 things that are not working:

1) If I press the Up Volume button, the system goes blank and only the 3 keys on the right are slightly illuminated. 

2) If I go to YouTube (or any other site) and try to play a video, the cursor spins and spins, but the video never plays. 

3) There is no sound from either the speaker or plugged-in headphones.

I have tried powering off and on, safe mode, soft resets, hard resets using the pin-hole button next to the SD card slot and hard resets going through the menu. I thought the problem might be that I didn't have an SD card installed. I tried that and it made no difference.

I've looked for [free] diagnostic tools and wasn't able to find a specific tool from Dell or anyone else.  I did find some package (I can't remember the name), installed it, and it said my motherboard was inoperative - which makes no sense since I had just gone to Marketplace and downloaded the app and I can go to Google and otehr web sites and so on.

So here are my questions:

   - What is wrong with this device? 

   - Do I need to return it to Dell? 

   - Has anyone else experienced similar issues? 

   - Does anyone have any other suggestions?

   - Does anyone know of any good diagnostics? 

   - Do I need to upgrade the firmware and if so, how do I do it?  (The Streak is already running Froyo 2.2 which I believe is the latest supported O/S).

Thanks!