Blew my Arduino. Did I wire this correctly? Hi,

I am currently doing a project and it seems that I may have blown my Arduino Nano (or maybe not). The power LED of the Nano was still on and I believe the L pin blinks once every time I press the reset button.

I wanted to use 4AA alkaline batteries to power my project. The servo is a continuous servo rated for 4-6V and 15-200mA from Parallax. Given that the Nano runs optimally when powered at 7-12V, I decided to buy a step-up converter (adjustable output voltage). It looks like this although I bought it elsewhere:

https://www.ebay.com.au/i/283603471149?chn=ps&amp;norover=1&amp;mkevt=1&amp;mkrid=705-139619-5960-0&amp;mkcid=2&amp;itemid=283603471149&amp;targetid=752505019384&amp;device=c&amp;mktype=pla&amp;googleloc=9071392&amp;poi=&amp;campaignid=1979582348&amp;mkgroupid=72745766764&amp;rlsatarget=pla-752505019384&amp;abcId=1139426&amp;merchantid=7364522&amp;gclid=Cj0KCQjwt5zsBRD8ARIsAJfI4Bh8cSOKugFrugHz-gA-s8nXclnO7H8iQ-WX46FRdhDLchwbl6UyWLgaAr4oEALw_wcB 

When I tried to test it with the servo running, my Nano stopped working after several seconds later. Did I wire them up wrongly? I also measured the output of the step-up converter when it was running with a voltmeter between the two terminals of the step-up's output. Would it be possible to short it that way?

Appreciate any help I can get. Thanks
It would be best if everything ran at the same voltage. (And it is necessary that everything uses the same ground.)  Which is possible as there are 5V Arduino boards.  Interestingly, the Arduino nano, according to this schematic, runs at 5V. 

In order to use the Arduino Nano at 5V, instead of using VIN / Pin 1, you should be able to skip the Arduino's 5V regulator and use +5V / Pin 4.  But this must be a regulated 5V power source.

Now, why are you having problems controlling the servo?

It is difficult to tell, but your boost switching power supply negative input may not be directly connected to the negative output.  With out a common ground, it may be difficult to create the proper signal to control the servo. 

To be specific, if the ground or negative side of the servo power supply is not at the same potential as the ground or negative side of the Arduino power supply, controlling the servo may be difficult at best and at worst you could burn something out on the servo or Arduino.

To check, measure with a volt meter to see if there is any difference between the boost switcher negative input and negative output.

To solve this problem consider using a USB power supply plugged into the Arduino Nano and powering the servo off the 5V at pin 4 of the Nano.  Or, keep using your 6V battery and 6V to 9V boost switching power supply.  Connect this as you are to VIN Pin 1.  The Arduino Nano's 5V power regulator should kick in and provide 5V at pin 4.