Above fine story demonstrates that, in many, many cases, any attempt at DIY will fulfil the sad predictions & predications implied in the title of this thread. One should keep in mind Hilaire Belloc's invaluable Cautionary Verse ~~

Lord Finchley tried to mend the electric light
Himself ~ it struck him dead, and served him right.
It is the business of the wealthy man
To find employment for the artisan.

~Michael~