Hi, gurus:
I have been a litle ausent by staff problems but I'm
back now asking for help:

I have an HDD

Barracuda 7200.9 ST3500641AS 500GB HDD FW: 3.AGK

whit the terminal output:

4096k x 32 SDRAM
TONKA4D - 1_Disk 03-15-07_20 S-76: 16

Head Mask FFFF - Switch to full int.
spin Ready
(P) SATA Reset

$$$ Switch to full int.
AM reacquired
Not Interface Age!
INVALID Cert Disk Code - Revised Resident ROM Required: AGM6L0
Command Inactive - No VALID Cert Code Detected

T>

When input commands the same answer:

INVALID Cert Disk Code - Revised Resident ROM Required: AGM6L0
Command Inactive - No VALID Cert Code Detected

Any idea what it mean?

Surface defects in the SA or damaged servolabels, probably due to the ageing. Also heads may be degraded.
And something wrong with the adaptives too (not good if as a result of previous incorrect data recovery attempts).

Not a walk in the park, I'd say.

_________________
• Remote RAID, NAS, SAN, VMware, DVR (CCTV), flash and tape recovery. Data recovery support.

As Dmitri said you previously, hard case.

Problably bad headsm or bad media or FW problems, or all together.

is a hard case, no for DIY. if data important contact with a local pro.