Most probably it is bad design, not something being faulty in there; however of course quality of assembly matters and someone assembling the device must have sufficient skills and training, otherwise such a thing may happen. But to my understanding, it is out of you control/influence and your knowledge.
I would agree with Christopher Estep in workplace SE that you should not take initiative you are not qualified for and formally charged with. If something will go wrong, you will be the potential scapegoat and there may be a risk to even being forced to jail.
What you should know about at your technical level is ingress-protection. Devices out there have to be certified to be operated in specific conditions (e.g. open air, environments of moisture, under rain, etc). Most probably devices you talk about should have a much higher International Protection (IP) marking than those operated within buildings, and the device should have been certified and must have appropriate IP marking on it.
If a device shocks people in a specific environment, this raises the following questions:
- Was the device certified to operate in these conditions?
- Was the device developed to operate in these conditions?
These are NOT your questions, but your management questions.
The first thing you must do when noticed of this risk to customer health is inform your boss in writing so that s/he will be then in charge of issue resolution unless s/he will order you to fix it (and then you will decide if you are qualified enough to fix it).
Further whistle-blowing is up to you. But you should know by whistle-blowing you can lose your job, and potentially risking your further employment. However, if you do everything per process, you may be considered as a hero.
- Inform your boss, if no proper (from your point of view) reaction, then;
- inform boss of your boss, if no reaction, then;
- go to executive people responsible for sales and legal (legal is important, because if someone will be shocked there will be a lawsuit or even criminal action against company), if no reaction, then;
- you go to authorities.
All these should be in writing, paper or email, and you should get a response in writing when possible.
In the conclusion: Electric/electronic safety is a subject being taught in educational institutions, and a course runs for a quite a long time. I am afraid, while you may get an idea what is wrong with the device, you will be hardly qualified to fix it.
But there's a good side of all this story. If you are so bothered by this case, take these safety classes; who knows, maybe you will become a great expert in it.
P.S.: I will tell you a story somehow related to yours. At the beginning of 2000s I was working for HP, and their field people identified that there was possibility of electric shock from devices called PDUs (power distribution unit) in the racks. HP invested in investigation and fix of this issue, and invested in its services organization to replace all PDUs in the field around the world. Every engineer was given a very sensitive phase detector to identify faulty devices to identify already failed PDU and protect self while working on the system. Thus in general, having this issue uncovered internally and fixed has many positive aspects (1) there will be no upset customers and no lawsuits regarding this issue; (2) there will be no damage to manufacturer's brand and service organisation brand; (3) the service organisation will have additional funding for fixing the issue.
P.P.S.: You will most probably find good technical advice from other answers. Be warned, that if you choose to implement them, you will be ultimately responsible for consequences, not that person who answered. That's why I deliberately refrained from considering your situation from a technical point of view without precise technical information provided.