Hello there,
as I had the issue that my HDD stopped working I will try to fix it. I hope this is the right place to get some advice:

HDD Data:
Seagate ST1000LM035; FW: LVM2; Part Number 1RK172-071, SN: ZDE3PXM7, DOM 11AUG2017, PCB: 100809471 REV A

Following situation:
Laptop hasn't been used for about 3 weeks -> HDD not showing in BIOS; external case doesn't work as well
HDD has not been dropped; doesn't make any sound when connected (no spinning, clicking etc)

What I did so far:
Ordered a donor PCB from another ST1000lm035 with matching Information:
Part Number, FW, LC P/N, PCB Number and Rev

Is it necessary to swap the Hdd FW chip in this case?

https://www.cheadledatarecovery.co.uk/2018/02/st2000lm007-st1000lm035-worst-hdd-ever/

Put your hand on the drive - can you feel any vibration at all? You can try swapping the PCB's to see if it spins but if failure wasn't connected to a power incident PCB failure is unlikely. If the data has any value to you, pass it off to a DR professional these are not the drives you want to learn on.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

Thank you for the reply!
Loosing the data on it is annoying but I have a backup from about half a year ago which is ok.

Can't feel any vibration at all. I've tried to put my ear on it when plugging it - nothing.

Would you recommend to just swap the PLB and check if it's starting at all and eventually solder the original bios chip afterwards?

Yes, but be careful not to damage the chip.

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A backup a day keeps DR away.