Are there LEGO plates without the word “LEGO” on the studs?
If you would like to get an official statement on this, your best bet is to contact LEGO's customer service. Here are some pointers you might consider when communicating with them: 

It seems like your question is about some of the electronic components. So, let's narrow down your question to those. The battery in the #42009 LEGO Mobile Crane has two studs on top with the LEGO logo on them. In addition, right above the studs their is a "2006 The LEGO Group" moulded into the lighter colored plastic. And there are also larger LEGO logos moulded into the sides of the unit. So, five LEGO logos in total.

This battery box has no alternates. It only came in this one version as evidenced by the BrickLink database, which is the most comprehensive database of all LEGO parts every made: ELECTTRIC 9-VOLT BATTERY BOX

I would also add to this that smooth LEGO studs always have the LEGO logo moulded into them, and this has always been the case since the earliest days of the company. There are hollow studs (like in some electronic pieces, LEGO Technic pieces, LEGO windows, hollow 1x1 round studs, etc.), however in such cases the LEGO logo will appear on some other place on the piece. The very few exceptions to this rule are when pieces are so tiny that it was simply not possible/practical to print a LEGO logo on them (i.e. hollow 1x1 round stud, some very small minifigure accessories, etc.)

Rather than being too generic like you did in your question above, when contacting LEGO's customer service, I would suggest to focus on two points. This can result in a quicker response and faster action. 


Ask them whether the specific electronic parts you are concerned
about (list exact set and part numbers) were ever produced without a LEGO logo (the answer will be no,
but for your legal case it's best to have this in writing directly
from LEGO).
Alert LEGO that someone is selling fake parts and claiming that
they are genuine. LEGO's legal department will be very interested in
this, which can help your personal case. It's even possible that
this seller has been on their radar already, and the information you
provide will be helpful to their case.


There are lots of imitation LEGO out there, but the companies making them do not claim that their products are genuine LEGO. They sell under their own brand names for cheaper prices than LEGO can provide. LEGO's legal department is fighting these companies already. Someone selling fake LEGO and claiming that it's genuine is a whole other level of criminal. 

Please keep in mind that if this is someone like a small eBay seller, they may have been duped themselves and they really believed that the parts they acquired are genuine LEGO. So keep your communication professional and you may be satisfied with just a refund. If, however, the seller is a larger online store specializing in fake LEGO parts and selling them as genuine, definitely let LEGO's legal department know and you may pursue your own legal case as well.