Perform a clean flash with esptool

I used one of the GPIO pins and made an LED blink. The code was running well, so I added save() to the end of my code to make it permanent, but the LED only remained on and none of the pins worked anymore. So I a few things for cleaning the save data, like reset() or as documentation has suggested, pressing the two physical buttons at the same time. When none of these worked, I assumed flashing the device will turn it back to its original condition but now I get this:

>{llœŸ|Œdà|Ädìb<‡ƒì{ÛcÄ#ŒóogžlgoœãìcpìŽ${$sdpònàƒdcoã|läl„c„û'oîdŒŽ$`˜'ÇlorǛ’'ld`8ûgàr„œÜãàc'ã|䇎‡cÄò'oï‡d`ng‡$'{‡“›g“l xóoà{Œœœãàäcgã|l‡cŒûgnçl`'l`o;Ǜ’'{d`{’“or$`sdŒÄgœŒóogŸŒžã„s'oŒl„cÇb8ƒdc$ä›l쓃„l$l~;lìddlgœâŒ$“$l$ä›lŒoàŽgä“'„„dlàÀcŽßcۄ‡c{c“ŒŽcbdl›“nŸg„ÛãolŸ|dl {$rl§Loading -491521 bytes from flash...
 ets Jan  8 2013,rst cause:4, boot mode:(3,7)
wdt reset
load 0x40100000, len 1396, room 16
tail 4
chksum 0x89
load 0x3ffe8000, len 776, room 4
tail 4
chksum 0xe8
load 0x3ffe8308, len 540, room 4
tail 8
chksum 0xc0
csum 0xc0
2nd boot version : 1.4(b1)
  SPI Speed      : 40MHz
  SPI Mode       : QIO
  SPI Flash Size & Map: 4Mbit(256KB+256KB)
jump to run user1 @ 1000
don't use rtc mem data
{$OÿLoading -491521 bytes from flash...

and then nothing.
I tried to flash it a few more times trying both sets of parameters written in tutorial page with esptool (just as I did in the first place and worked well) but it seems something wrong has remained on the board

I'm assuming ESP8266 and you've added the reset buttons?
There's an erase_flash command you can use that will clear everything. See esptool -h for more info. Then reflash with your espruino binaries and hopefully all good.

Thank you! yes! that did the trick.

The board I have is a Nodemcu V3, so the physical buttons I was mentioning were the RST and FLASH.