smartctl reports bad sectors, badblocks does not find any

[Juan R. de Silva]

I did the stupidest thing I could as to forget that I was running on 
battery while installing FreeBSD on a free (1st) partition. and I found 
the laptop shutting down when it was too late.

After this event smartctl consistently reports Read Failure starting on 
LBA 26203589, Current_Pending_Sector 1, and Offline_Uncorrectable 4. 
This block is within partition in question. Thus I know I damaged hdd 
within its boundries.  

Simply formating this partition certainly did not help.

I've run dd if=/dev/zero of=/dev/sda1 both starting with the reported LBA 
and then on the entire partition. And I still have same report from 
smartctl

I run badblocks on the partition firs in non-destructive and then in 
destructive (read/write) mode in both cases badblocks reported 0 errors. 
But smartctl still gives me the same report.

In all the cases I run smartctl -t offline /dev/sda1 just to ensure 
smartctl updates its data before I run final smartctl -A /dev/sda

Any suggestions folks? It drives me crazy. I'm fighting it 2 days for now.