Fixing my laptop after installing Win 10

This wasn't so hard.  Run the built in BIOS diagnostic.  And now the Start Menu (pure software) works, and the power button (Hardware but with a lotta software messing it up) works.  a
   Some website explained the way to get into the BIOS diagnostics was to hold down the ESC key while you hit the power on button.  And this appears to work even while the power on button isn't working.  According to a website, the BIOS diagnostics have been standard in HP laptops since 2009. Which means a lot of 'em have it.  On my HP laptop, a 2014  model, the BIOS diagnostics do start up, but they don't give you any messages on the screen except for one, They ask if you want to skip the disk test. 
   And the diagnostics reset a bunch of internal variables, which revived both the power on button and the start menu.  This shows a crappy design on the power button.  Any decent power button ought to assert the reset line to the processor and the entire motherboard.  When reset is released, all micro processors jump to the starting address, (top of memory on some, bottom of memory on others) and start executing code.  The purpose of reset on micro processors is to regain control and start running the program from the top, no matter how messed up the software is.  That ain't happening on HP laptops, some kinda hardware and software kluge is breaking control of the reset line, and the machine fails to start when the button is pressed.  Running the BIOS diagnostics fixes the software part of this kluge.
   Good work HP engineers.   I wonder what else you have screwed up.

Win 10, no Start menu, Power on button broke

So after running a bit after my upgrade to Win 10 I find.
1.  The advertised "start menu" , a replacement for the trusty "start menu" in Win XP, is nowhere to be found.  Some web searching tells me that this is a common problem.  A bunch of fixes were offered,  I  have tried a few of them with no luck.  Without the new and improved start menu, the only way to reach the "settings" app is thru Cortana.
2.  From the settings app I tried out Windows update.  It trundled away downoloading a patch for office and then failed.
3.  The power on button doesn't work,  Press it to start Windows and nothing happens, I get a blank screen.   Work around,  power off the laptop.  Unplug the charger and remove the battery.  Count to ten. Replace the battery and the laptop powers up and runs windows.
4.  Task Manager shows something called "OneDrive" is soaking up 300 Meg of Ram.   Apparently OneDrive gives access to "the cloud" for file storage, after you spend money.  Since I have 600Gig left on the hard drive, and I don't trust "the cloud"  I'm thinking of removing One Drive.  

Antique Laptop revived, XP lives

Couple a weeks ago, getting ready for a trip, I pulled antique laptop out of his carry bag and fired him up to charge his batteries and update his software.  You know how it is, leave the laptop on the shelf for a little while and every piece of software needs an update. 
   Arrgh.  he would not fire up.  LEDs blinked but the screen stayed dark.  So Antique Laptop stayed home and then sat out on the table for a couple of weeks 'til I got around to him today.  Antique goes back quite a ways.  I gave him to youngest son to go to high school with.  That was maybe ten years ago.  Youngest son is hard on his gear, and it shows.  Scratches, scraped off paint, ding marks.  Somewhere along the line, youngest son bought a hotter new laptop to make his games run faster.  Antique Laptop came back to me.  So I cleaned the games and craplets off the hard drive, zapped endless virii, applied my list of Windows fixes, and he ran pretty well.  Ran my C compiler, Office, and my CAD programs.  What's not to like?  And he runs XP, which is higher performance that the follow ons, Vista, 7, and 8.
   Thinking back over Antique's life, I remembered youngest son showing me an electronic module behind the screen bezel that had given trouble in the past.  Why not?  I  pulled two screws and popped the bezel loose.  The module was right there where I remembered.  So I unplugged it, blew some dust out of it, and plugged it back in.  Voila, screen lit up, XP booted, and happiness roams the land.  I don't have to learn Win 8, replace elderly software that won't run on 8.     Motto of the story.  The most likely failure in electronic stuff is connectors.  Over time air gets in, oxidizes the pins and sockets, and they stop conducting electricity.  Connecting and disconnecting often wipes the oxidation off, and it works again.  If it just stops working, take it apart, and put it back together.  You have a pretty good chance of fixing it.
   It's an HP Pavilion ZE4900.  Still looks pretty good.  In fact I bought him a new battery this winter. If you are looking at buying a used laptop, this one is durable.