Hi If anyone can advise what I should do first that would be really helpful. I have extremely limited IT knowledge: I have a VPCEB4C5E, Intel Core TM i3-380M, 2.53GHz, 320 GB Serial ATA (7200 rpm), 4 GB 1066MHz DDR3-SDRAM, ATI Mobility Radeon HD5470 512MB. Bought 2011 at a huge expense.

have BT Netprotect Plus McAfee, 

always had overheating and had new mainboard in  feb 2014, but recently internet got slower and impossible to use

decided to opt for win 10, over 3-4 days it kept powering off then, crashing about 20 mins of being on, now never been the same again

reverted back to previous time saved from external hard drive, but repair issues kept happening then powering off mid repair, mid safe mode installing, then no vaio symbal at start up, then a succession of blue screen warnings, then did factory reset unplugged battery out press power button, assist then all seem to go well it went through the motions then I thought I would just install office it crashed half way through BSOD error then back to random blank screens power on power off - I have photographed screens as they have occurred.  

I managed to get it back to win 7 factory settings again after BSOD then shut down and that's how I have left it till I get some advice... the last screen said 

BlueScreen 6.1.7600.2.0.0.768.3  Locale ID 2057 (then additional info)

also got

Startup Repair cannot repair this computer automatically

and mshta.exe instruction at 0x728f1ada referenced memory 0x06fedffc. Memory could not be read. (was in start rescue)

and check BIOS updates disable BIOS memory options ... STOP: 0x0000009E

well if anyone can make sense of that lot, it would be much appreciated and any ideas as to what I should do first? update windows?