Criminal charges: ????????? Oh come on now ...............

Not a criminal charge necessarily!
If you are in the USA (or any other part of the world given to law
suits on almost anything the least bit out of the ordinary) possibly
an action by an inurance company to recover damages i.e. death.
Can you just see, say, a CNN headline "I'm afraid I fried my friend"!
Quote: Joe whatshisname in Hot Water Springs, in some state or other,
had tinkered with his hot tub to make it hotter than designed.
Exceeding the US Underwriters Lab. temperature safety guidelines by
several percentage points. He then invited over some friends, one of
whom had an unknown heat allergy. Friend collapsed, was rushed to
local hospital where despite ice packs and other treatment she
expired.
case goes to trial in ..........
Settlements in cases such as these, if negligence, even unintentional
or uninformed can be proven are normally in the several million dollar
range etc. etc.
The manufacturer of the hot tub originally named as co-defendant
declined all responsibility because of the home-made modification to
the heat control That has been accepted by the plaintiff. The sole
defendant will now be the homeowner.
In other words if you modify it don't tell anyone and hide the
changes!